Here, have a thinkpiece. I would recommend against reading it in one sitting. The numerous spots where you'll stop and go "Well, actually. . ." regarding my analyses double as spots to step away and grab some food and/or sleep.
Everyone differs in their enjoyment of Smash as a series and why they personally spend time posting on internet forums like Smashboards. Goes without saying, right? Well, I'm here to make the case that Smash 4 brought fanbase members to a crossroads in their enjoyment of some game elements, based partly on factors inevitable 15 years into a series and also on consciously changing attitudes. This post is not meant to argue that one way of enjoying the series is better than any other, but rather to explore how the fanbase got to where it is today and how it could proceed, with implications for K. Rool and the Kutthroats.
In the wake of Melee, Smash had the allure of being not just a newly-popular series but one with a vast amount of untapped potential. Going into Brawl, there were scores and scores of big-time Nintendo characters and content to include from games recent and old, from veteran and new series, and on a more-modern console that was doing gangbusters at the time.
With that surplus of options in front of them, people really started having fun making support groups to post why their preferred character ought to become playable and advocating for their inclusion (more on the efficiency of that later). Users not only rallied behind people like Diddy and Dedede and shared how they might play, based on their history of appearances, but also built grassroots support for more obscure options like Geno. Later on, once the demos started hitting stores, people also spent time analyzing gameplay footage to see how the mechanics compared to Melee. Fun fact: People saw tripping and had no idea what the hell was going on, to the point of deeming it "ink-dropping" as an advanced technique.
You might be asking yourself how any of this differs from Smash 4's speculation scene; there are several answers. Compared to Smash 4 and onward, there were only two Smash games to give precedent for roster picks. The sky was the limit in terms of who you could suggest while being taken seriously, without much talk of who was likely based on patterns. There were also so many big-name characters left that vocal character support was the norm among fans. Everyone had at least a few characters they were particularly passionate about seeing playable, and many got their wishes. Brawl's roster did end up getting flack, but from my experience, that was less due to the characters chosen and more because fans' expectations had gotten so high, they were expecting a roster count in the high 40s or low 50s (the unlockables being largely veterans threw people for a loop).
So, to touch back on the "enjoyment" angle, Melee left most fans satisfied with gameplay — it is full-on revisionist history to say people thought Melee was "too hard" before Sakurai made that claim — but wanting in terms of characters and content. Going into Smash 4, on the other hand, people were relatively happy with the latter and openly critical of the former. Tripping was essentially, and deservedly, considered a meme in terms of a terrible choice, and people had no shortage of character-specific gameplay complaints to offer. "Who on earth balanced Meta Knight that way?" "Why does Dedede invalidate multiple characters with chaingrabs?" "Why do Snake's hitboxes stretch out -that- far?" And so on. On the whole, character support had taken a backseat to mechanical balance fixes (a not-insignificant number of people professed Brawl would have been their personal "perfect Smash" if not for the gameplay).
That's not to say the focus on characters evaporated — there were still a handful of characters people supported in a way reminiscent of that Brawl era — but changes were starting to creep in. The existing characters already satisfied a good chunk of fans to the point where fewer were invested in newcomers, fewer of which were widely agreed-upon. Instead, the people who stuck around on forums, and the new posters who read the terrain, had fun debating who was and was not likely. By far the biggest emerging area people would look to in these debates was upcoming releases. The focuses on likelihood and releases weren't altogether new phenomenons, but it quickly reached a point where most people's perception of a character's likelihood linked directly to how promotional of a new game they could be. Not coincidentally, the scene had reached a state where not many were bothering to build up support for Geno-esque characters anymore. Why bother? They're irrelevant! Can't promote a thing! Not going to happen!
Concurrently, people's perception of uniqueness changed from pre-Brawl to pre-Smash 4. In the aftermath of Melee, proving a character's uniqueness more or less meant demonstrating that that character couldn't or wouldn't be a clone. As Smash 4 and its newcomer reveals got underway, however, "unique" came to mean that a character would bring their own gimmick, mechanic or prop (my observation: people who tout uniqueness but struggle with moveset-making promote candidates by saying "He/she/it would hit you with <insert prop name here>"). In that way, uniqueness started becoming a cudgel people would use against characters they felt didn't measure up (inter-franchise character wars contributed). An increasing number of people also would start proclaiming that "they didn't care" what characters were added so long as they were "fun to play," a metric often mentioned in the same breath as uniqueness.
In the end, Smash 4 and its DLC were released with all but a single-digit number of big-name requests, gameplay that was almost universally considered an improvement from Brawl, and a large amount of miscellaneous content across two systems. In other words, the series reached a point where a majority of online fans no longer desired different characters or gameplay than what they'd ultimately received. Sure, already-satisfied people had and still have their personal wishlists, but on a broad scale there's not much investment in new content added so long as it's "fun/unique." Users along these lines often debate likelihood/new games to a fault and then get blown away by newcomers who fall outside those criteria, who in turn make the users even more satisfied. In my observation there's a lot of overlap between these users and the ones who will very quickly become unhappy upon mention of the mere prospect of character cuts. ("How dare you! Someone out there enjoys those characters!")
Where does the crossroads come into play? Well, as more and more people become satisfied with Smash as-is, it becomes easier and easier to look upon anyone carrying on that Brawl era of concerted support group advocacy as alien. I think there's a misunderstanding in place that anyone who vocally supports anything new or different in Smash necessarily is criticizing what is there. That's not always the case (though criticism isn't inherently a bad thing either), it just can come off as such when the lion's share of those posters' comments are about what -isn't- in the game that they want included, versus what -is- in the game that they like already. It is worth noting that, as Smash becomes more of a behemoth, for worse and better, these sorts of advocates have more of an incentive to pipe up; if they get their way, it's on a larger scale, with a greater payoff for characters and series in particular.
But with propositions for change becoming rarer and rarer, it becomes easier for the majority to dismiss loud requests for K. Rool or Ridley as ravings from unappreciative lunatics, or shoot down anyone calling for gameplay closer to Melee's as part of a "vocal minority" stuck in 2001. That, of course, can turn people in that minority defensive, demeaning those who don't share their desires as "sheep" or "apologists." The majority responds by smearing whole fanbases as "toxic," hoping <insert request here> doesn't happen "so their fans will explode," or policing "hype" for indicators of "salt." On and on the vicious cycle goes, and completely needlessly. The two groups are perfectly capable of enjoying the game and lead-up in their own styles, even though their approaches to the game don't align as they once appeared to.
I should probably mention here that after Smash 4, people should reframe how they think about the internet posts they make advocating for a character or change in Smash. It's been known since 2008 that Nintendo people like Nate Bihldorff lurk Smash sites, and it's a safe assumption that some requests get back to the developers once they become repeated a certain amount — anything from the huge push to remove tripping to more recent minor things like Sakurai being aware of the perception he favors his own Kirby games and Fire Emblem. But given the confirmation post-Smash 4 that the series' design documents are finalized years before the titles are announced, online Smash requests really only matters in terms of influencing the -next- game, maybe DLC or a ballot nowadays in lucky cases. Given the paucity of Wii U era content, there's a chance Smash Switch will break that trend, but that's something we'll only know for sure once the post-game interviews come out.
To wrap this massive wall-of-text up, I think it would be an interesting fanbase experiment to bring onboard a new Smash director who announces he's pulling a Thanos and wiping out half the roster, without naming which characters are getting cut. Would that knowledge cause the fanbase to revert back to its Brawl iteration and start focusing again on the characters and the nuances of their movesets in "the greatest character game in the world?" How would the pressure of a telegraphed smaller roster affect how newcomers are assessed? To what degree would fans apply the patterns or knowledge they've developed (or think they've developed) this far into Smash's lifespan if the series were, for all intents and purposes, getting rebooted?
For me personally, though I have no interest in speculation outside of K. Rool and Ridley-specific stuff, those would all be questions I'd enjoy seeing answered somewhere down the road.