winstein, that question I posed was actually a rhetorical lead-up, as I was under impression Kirby was treated fairly well and reasonably.
I have to disagree on the "mistreatment" argument. See, I was making the case for Mario being mistreated too, even though you guys say, "but Mario has tons of playable characters, tons of stages, 3 hours+ worth of music, tons of spirits", but then I point to gaps in the coverage in the Mario spinoffs, the Mushroomy Kingdom stage being a nuclear wasteland, the voice direction for practically all Mario characters being shit, the boring Mario Finale, the Negative Zone (yeah that was a thing), Mario treated like a literal punching bag in move demonstrations. I was still dissatisfied with what I got because what I got wasn't perfect.
Honestly, in the end though, I just want Mario characters to have a better voice and a working Final Smash (which was working in 4 but terrible in Smash Ultimate).
The same thing probably applies to Kirby as well. I think in Kirby's case, Sakurai was being really choosy with what he had and what he thought best represented Kirby. I think the lack of spinoffs (beyond Air Ride and Mario Kart) isn't really a Kirby problem, it's a recurring problem throughout Smash Bros., and I don't think I can actively blame Sakurai for it as more as I can blame the self-limiting nature of crossovers. It's a shame Mario doesn't get a single track from Mario Strikers and barely anything from the other Mario sports or Mario vs Donkey Kong, but I think we'll be complaining all day about rather minor grievances and will be constantly setting up ourselves for disappointments.
And people were complaining about Metroid having only two characters for the majority of Smash's lifespan, and Metroid repeatedly gets lava stages.
And people were complaining about DK's mistreatment as King K Rool was also absent for the same amount of time, and DK always gets Jungle Stages and 20 bajillion "remixes" of the DK Jungle theme. And DK and Diddy sound like shit. I think that one may be one of the more legitimate ones, especially King K Rool's absence, but there are some elements of "ahh, it's not perfect, so they're being mistreated".
And people were complaining about Fire Emblem having tons of sword fighters and they had a generic shit stage being Castle Siege, and how there's no variety in the Fire Emblem characters, even though others counter that Fire Emblem is overrepresented and deserves hate by jealous fans of DK and Metroid or something.
And people were probably complaining about the Gee Wun reps and want more gen variety. I myself find the music selection to be pretty weak, just a lot of battle songs (yeah it's a fighting game but Persona shows that such tracks don't have to be so homogeneous), but again, it's not like Pokemon is known for having amazing soundtrack.
I guess this just comes when series start getting big and get more playable characters. With small series, you are just happy you got anything at all. No one is complaining about the lack of Ice Climber playable characters or the lack of Mother playable characters. Or at least, not as loudly as fans from the bigger series.
Oh well, just mod the game. People are working on it, and once SaltyNX is out and that patching nonsense is history, you can add all your favorite tracks in the game. It's still a crying shame that Nintendo hates this sort of thing when people seek fine solutions for problems they have with a game.