I feel like origami king's "rpg" mechanics work pretty well, they're just really weird and unique lol. Instead of rewarding exp the battles reward coins which get you better gear and more stuff.
And then it's not like the mechanics are dumbed down, the battles and bosses are the most complicated and difficult in the whole series. Taking a big hit in Paper Mario 1 is taking like 7 damage, taking a big hit in Origami King is taking more damage than you even have max HP because you screwed the mechanic up.
Super I actually thought the RPG mechanics were completely vestigial and the gameplay was dumbed down to the point of being pretty boring. The only reason I'd give to play that one is the story.