Nah, it's simply development time based. If they made every character have properly unique custom moves they would spend so much development time on that I doubt they'd even be able to add any new characters to the roster at all.
Palutena got a lot of customs I guess because they started with hers and then decided not to continue on? Or because Palutena as a newcomer just didn't bring anything particularly exciting to the roster compared to others like Villager, Rosalina and Shulk.
Honestly, Wario's moveset can be mostly traced back to his status as "Warui Mario", with some hints of his games added in as well, most notably the way he swells up as he attacks and of course his bike.
Is there more that could've been added from games featuring Wario? Sure. Then again, the same can be argued for Mario. Mario's tilt attacks and aerials don't seem to have any origin at all, and by extension, neither do Luigi's. Green floaty fireball? Makes no sense. Up+B? It makes a tiny bit sense for Mario and none whatsoever for Luigi or Dr. Mario. The cape can now turn things around and reflect projectiles? Gosh, why not use it to fly instead? And hey, since you got that nice FLUDD on your back, why not use THAT for recovery?
And if you look closely, you'll see that aside from the more polished newcomers, a lot of characters still have this, but with some, you simply wouldn't want it any other way. Yes, Mario could use his cape to glide instead but the "flip things around" mechanic in Smash is too much fun and the coin up+B is too satisfying.
Meanwhile, everyone talking about Wario's ground pound seems to forget that it's a move commonly used by Mario and Luigi as well, yet Mario doesn't even have it as a down-throw.
That having been said, I'd personally like it if Wario's dash attack could be replaced with his shoulder bash. That's the only real change I need. Yeah, I do think his current dash attack is funnier and gives him more follow-ups and gimp options, but Wario is currently lacking a kill move that isn't too laggy, rangeless or situational.
The philosophy behind his new forward smash was making him stronger and giving him more range, at the cost of removing what's canon about him. Changing his dash attack would solve those issues quite well too.
Making him bash more like Captain Falcon, Palutena, Samus and Ganondorf could potentially make him stronger and please the fans immensely as well.
Hell, even the four I just mentioned have immense differences in their shoulder bashes. For Samus and Captain Falcon it's more of a combo move, for Ganondorf it's a reasonable finisher (then again, what isn't) and for Palutena it's both a finisher and a strong counter because of the intangibility on her shield.
I'm sure Wario could have something that makes him unique as well. Have the hitbox out longer. Change the launch trajectory. Give it Yoshi levels of distance. Give it a cool sound effect.
It's really the only change I see as the most obvious one, and I can't believe there's not a single mod out there or many "proposed moveset changes" that actually bring this up.
