So basically Nintendo characters are now trash. Many Nintendo series survived because of their inclusion in Smash Bros like Fire Emblem & Xenoblade, so just throw any possible new Nintendo character out from being considered being playable weakens many potential series because now their not good enough or worth the time. ARMS did sell extremely good but it did drop like a bag of bricks with the people who bought it to a point where the series future is in danger of not continuing. Nintendo could strengthen it's own series by including ARMS into Smash Bros, but instead we're just going to focus other companies and just throw the rest of the Nintendo series under the bridge.
Third parties are great but they're not feeling special anymore and just makes the rest of Nintendo series and characters that aren't ever going to be in Ulimate just look like trash.
Also no, if we're never going to get another Nintendo character added into Smash Bros Ultimate ever again the Piranha Plant deserves all the hate it can get since it will a constant reminder that everything else that Nintendo owns is complete garbage because they went with a generic enemy as their last Nintendo rep. Instead of choose the other characters that people have been dying to see make it in they wanted to dumb the barrel and scrape it so hard they're bringing up dirt.
You're the only person calling Nintendo series trash. Saying they are less enticing in the current circumstance does not mean that Nintendo characters are trash or bad. X not getting into Smash as a playable character does not mean that X is bad and you
have got to break yourself of this mindset. Not everybody can be playable in Smash and not every character that isn't playable, is not playable because of some inherent judgment on their quality. It's such a closed off mindset to even look at character selection from and I don't understand how you just consistently arrive at these same conclusions. A =/= B does not allow you to say that A = Z.
Xenoblade didn't survive because of Smash, it survived because a whole bunch of dedicated fans put together a giant operation to convince Nintendo to localize it and bought the game. Being in Smash didn't hurt it, but I'm not letting you take away what people put tons of effort into and the commitment Nintendo made to Xenoblade regardless of Smash (X came out right after Smash 4 and didn't sell amazing, but then 2 sold considerably better without any Smash cross promotion).
Fire Emblem is once again this stupidly specific set of circumstances and is legitimately the only time Smash has genuinely been critical in the continuation of a series. Punch-Out (Wii) doesn't have a sequel despite Little Mac getting in 4. Ice Climbers have never come back outside of Smash. Despite Lucas being a really popular Smash fighter, we still can't get an official localization of Mother 3. Captain Falcon being in Smash has not resulted in F-Zero continuing on. Pit only got a new game because Sakurai went all in on a new Kid Icarus, and has not been seen since. Banjo & Kazooie aren't even being capitalized on beyond Rare Replay. Being in Smash is far from some promise of a future for a character, and most of the evidence is to the contrary.
Nintendo is currently in a position where they don't really need to strengthen their brand with Smash promotions of characters. They have plenty of successful titles already that they can reliably count on and frequently push for innovative new titles on their own anyway. The Nintendo fans are already all playing Smash and a **** load of their other games anyway, so Smash can serve as a product to introduce new people to their IPs and their console at this point. I guarantee most of the population who played ARMS plays or has played Ultimate, I would not say the same for those who played Persona 5 or King of Fighters or Dragon Quest. That's not to say you can't appeal to people who play Nintendo games, but it explains why the thought process is so prevalent in Nintendo's decision making. Big names mean big headlines that mean continued success of a product, and this particular product already basically represents everything major Nintendo has to offer outside of a couple of specific additions. It strengthens their brand by continually attracting more people, and Nintendo cares way ****ing more about their overall brand than they do most of the specifics franchises in that brand, particularly the lower selling and more niche ones. Again, that's not to say there isn't a place for Nintendo characters, but it makes sense to see them as lower priority at this point given how much Sakurai has already achieved in representing Nintendo in the base game and how Nintendo have actively stated they want to use Smash as a launching point for people into their recognizable brands. A new player to Golden Sun for example might be worth a bit, but a brand new fan to the Switch and let's say, Mario games in general, has so much value to them (in addition to the fact that many of these third parties also please tons of people already playing).
Third parties don't have to feel special anymore. I don't get why that matters if they do or don't, they still attract huge headlines and excite millions of players.
And again, with Plant, you've repeated this same sentiment ad naseum and it still rings hollow every time. Piranha Plant was created to be different and fill a specific niche with players. You were not the target of that niche and constantly throwing a tantrum about how Plant stole your character's slot comes off as immature. Sakurai didn't tell you your favorite characters not in the game were trash, he told you that he was making something for someone besides you. You actively do more harm for character support when you act like this if I'm being brutally honest because of how entitled and consistently hostile it comes off as.