Think, Shroob, think!
If all the characters were already chosen, then they would have already known they would get some sort of backlash from the core audience just by knowing which characters they chose, thus they could have negotiated for a character during that time to balanced it out and they ended up being the last character. Sakurai already knows how his fan base acts, so having two Nintendo 1st party shills and a character that got in due to popularity and him being pressured into it (which actually applies to both Steve and Kazuya) and the other two weren't asked for by that core, he would have already known in 2019 that this pass is lackluster to the core audience and appeals mostly to people outside of Smash.
Now, which do you think is more intelligent to do, assuming you can only do one and not both: appeal to people who don't already play your game to get more of them, or appeal to the core audience you already have who are already playing your game. This is something that a lot of companies are doing incorrectly right now by appealing to smaller groups outside their audience and it's costing them money and public opinion and more often than not it pulls in very little to no one from that smaller audience while losing from the core audience. The smart play would to have made FP2 50/50: keep Steve, Pyra/Mythra and either Sephiroth or Kazuya but make the other three something like Lloyd Irving, Crash, or Reimu or any number of older requests like Dixie Kong or Krystal or Isaac. This way you still appeal to the most people outside of Smash and do a little shilling but show you are listening to the core audience.
Also, I hate that I have to explain this again, but the list of Brawl Era and earlier requests is HUGE! The reason that the older fan base seems insatiable is because Nintendo and Sakurai grant so few requests from this list per game that the list gets the chance to grow more than it has the chance to shrink. If Sakurai had begun putting in somewhere between five to ten long term requests since Melee or Brawl, the older fan base would have been very quiet by now and honestly more supportive of newer character requests. Logically, this is because they already got what they wanted and thus don't feel like they constantly have to compete with the picks of a newer generation of gamers, and since deep down people want more content for Smash they would be more open to those choices.
You also need to consider that at it's best, Smash gives characters a new chance at life because of the support and the praise older characters can get through getting into Smash, and at worst it's a respectful tribute to what they have accomplished and it makes gamers of that era feel recognized. Thus, a lot of older gamers already have gamer nostalgia for how games used to be and used to be made, and video games have progressed so far in such a short time that a lot of gamers would like their favorite old series to have a chance with modern day hardware and software. I mean, Crash, Spyro and MediEvil remakes speak for themselves, as well as FF7R, and everyone is still clamoring for a remake of the two B&K games AND a completed promise of the trilogy.
Now imagine being in that situation where your favorite older series has a chance to be reborn or at least given proper recognition, but since it's been so long since you've requested it, gaming has changed so much that now you are competing against the requests of tons of kids across the world who want THEIR character in just because they love their game that has a bunch of costumes and funny dances in it. This is where the competition comes in, and honestly this is about a third to half the reason the fan base is so toxic to each other, because you have clashing desires based on different ideals.
