I don't mind new things, and in fact I enjoy some of the original characters in quite a few Mario RPGs, but there's a difference between adding a few new characters and oversaturating the game with them just for the sake of it. Adding to that, Super Paper Mario's characters feel incredibly... non Mario-ish. I don't know. I can't really explain it, but with the first two Paper Mario titles, all the characters feel like they belong in Mario. Even the characters who aren't based on any existing characters, like Crystal King, I could see appearing in any other Mario series (which bugs me that it doesn't work that way, but I'll get to that later). But SPM's have a certain style to them that just doesn't work for me. They're made of basic shapes and tbh I think they look ugly.
But this is all beside the point. The game revolves around Count Bleck and Tippi, which is a big no-no when the game is supposed to be about Mario (hence the name). And really the only reason any of the main cast was some prophecy. It kinda feels they borrowed elements from a cancelled other project IS was working on, but I'm just speculating here.
