Diem
Agent of Phaaze
The difference is that Waluigi is a spin-off character who has no real prominence within his main series, whereas Ridley is the most notable Metroid character next to Samus as her arch-nemesis. The characters have a fundamental difference in terms of identity and appeal, with the only similarity they share being that they were both excluded from Smash, therefore, memes.I think my biggest issue with this line of logic is that there's no clear line between "meme popularity" and "genuine" popularity with someone like Waluigi. For something like Shrek or Goku or Ultra Instinct Shaggy? Yeah, that's a different story, because they're ineligible characters.
But Waluigi isn't. And you could just as easily chalk Ridley's popularity up to the Too Big memes. I, personally, know not one, but three people IRL who wanted Ridley solely due to him being "Too Big" and them wanting to see how he'd end up working, none of them ever having played a Metroid game...but they knew about the Too Big memes.
I'd go as far as to say that most of Waluigi's support is absolutely genuine. People like the character. There was genuine backlash and uproar when he wasn't in Mario Kart 7...and ever since then, he's never missed a spin-off game.
Though of course it's difficult to get the objective answer without doing some sort of full-on research study. Anecdotal evidence isn't very helpful. I had a really cringey encounter with a Waluigi player in Mario Kart 8 at a Switch event a couple years ago at the mall, but I wouldn't use that to generalize all people who play/want to play Waluigi. Which is why I try to look at the characters for what they are and use that to determine why they have appeal and support.
I'd be down to see them do something more substantial with the character. I wouldn't turn down a Waluigi-focused game. I'm not a Waluigi hater or anything. I just think there's a few more characters we could add first before we add another Mario character.