It's been brought up before, but I concur that the notion of "reps" is pretty silly. I don't believe there's a certain quota of characters that a series has to fulfill, nor do I think there's any upper limit to how many characters a series can have. I support characters based on their own merits and how they would make the roster better and more diverse, not because "X series needs more reps" or "Y series has too much reps".
Like, I'm a fan of Metroid and all, but I don't support Ridley because "muh metroods" - I support him because he's an interesting character who'd bring something new to the roster, to wit: big flying aerial fighter. That he has huge fan support is just an incidental, but very much welcomed, detail.
Likewise, I think K. Rool and Dixie would be cool characters and would be fun to play. I'm not too concerned that Donkey Kong doesn't have that much content relative to other series.
It's also why I'm a bit skeptical about some of the cut vets. I don't have anything innately against the likes of Young Link or Pichu (I actually really like Pichu, but that's beside the point), but I don't think they're all that interesting in the grand scheme of things. I feel similarly about Roy, though I think he'd be much more capable of doing something different compared to the previous two. I think they definitely could do something distinct (Young Link with his masks, Pichu with the discharge mechanic, etc.), but I'm hesitant to suggest that they'd be the best choices when there are other characters that I just think are more interesting and memorable.
It's total bias on my part, I'm aware of that fact, but that's just how I feel. I'd rather play characters that I like and think are fun than characters that are shoehorned in for the sake of "reps" or to be the token Zelda / Pokémon / Donkey Kong / Metroid, etc. character.
I support Wonder Red and Inkling, in spite of their respective difficulties, for similar reasons. I really, really like them and I think they'd be really, really fun to play as~