There have been nearly twenty third party characters in Smash, and I don't think that anyone would say that the characters that we've got so far have lowered the bar to the level where someone like Bubsy would be expected.
(I don't know how many people have played Bubsy, but I played it on the SNES - it was a terrible Sonic the Hedgehog knock-off designed by someone who seemingly wanted to cash in on the craze without understanding why people enjoyed those games to begin with, leading to a game where the level design encourages you to go fast but you die in one hit or if you fall from a large enough height)
The third party characters that we've got have had some combination of a ton of history/influence (ex.
), long-lasting popularity or demand when it comes to Smash (ex.
), or are generally seen as one of the best examples of their genre. (ex.
) Even if there are cases where people might not have wanted a certain character in the game, I feel like most people would be able to understand why the third party characters that are currently in the game have been included.
Third party characters have been a part of Smash for a decade and a half now, and I can't think of a single interview, comment, or hint that they considered including any sort of flavour of the month meme pick that people prop up ironically because of how terrible it is. I can't imagine that we're going to get diminishing returns to such levels that Bubsy seems likely, let alone reaching the point where the developers feel the need to jettison most/all third party characters because of it.
I apologize for the rant; I've just been dealing with this sort of "third parties need to be cut" or "we need to limit third party characters to cartoony platformer mascots" since the Smash 4 days at least, which got really frustrating as someone who liked playing as Snake in Brawl.