I think things like Diaz or Sonnen getting title shots hurt the UFC a lot more than a flashy entrance. I like flashy entrances as a way of giving fighters a chance to show some personality. I'm not down for a whole set piece (like the previously linked Thriller fighter) or someone being an asshole, but I think a wacky costume and/or quick choreographed routine is a good thing.
Plus, a few choreographed routines may make McDojo warriors tune in, hey-oh!
Here's one from religious nut Kimo:
And here's a great one from Mirko Cro Cop:
I love flashy entrances, I think it adds a lot to the spectacle of a match. Kind of like ****-talking your opponent, it all adds to the atmosphere.