Well, I enjoy that Bowser is still around. Sure, it gets a little annoying later on since Bowser never gets any smarter, but that's who he is. A Mario game that's actually challenging would be nice (it better come soon, Nintendo!), but I would never want to see Bowser be gone for good.
He keeps trying again after he constantly fails, he has the intelligence of a villian sure enough, he's the perfect boss in my opinion.