I'm pretty sure Hello Kitty is already well known all around the world.
I'm not doubting that. I'm also not doubting whether it has a place in this game, give what else are already in. I'm just half-surprised to see Sanrio lending out their characters for free. (Someone from Nintendo once mentioned that they'd be glad to make costumes if they don't need to play anything, if I recall corectly.) I guess they don't mind this free advertising, after all.
Personally, I'm still waiting for the rest of the Smash characters. It feels strange that Roy and Ryu don't have any.