Why must you all hate so much?
What's wrong with ''filler" characters as long as they have personality?
And don't say Waluigi and Daisy don't have personalities. They're not exactly filled out ones as much as the main cast, but they are there and they are both fun equals to their ''counter parts."
As for Waluigi who is more my personal favorite, his meme status actually has nothing to do with it. I love that this guy who probably cheats tremendously to win things, claims everyone cheats the moment he loses. It's comedy rich.
He's also shown to be quite romantic despite you know...having the appearance of someone who wouldn't be looked at twice, yet he still won't give up on his softer side because he's not a god damn quitter. God bless him. He tries. And if that isn't relatable what is?
There's little details about him in his sports appearance spin-offs that can easily make him quite lovable without having to get into his meme status for sure.