If I was a pro I wouldn't want my disc to look like it's some plastic. I would want that disc to be mean looking and scary so you would scare your competitors whenever you pulled it out and scare away their discs if they try to land nearer your awesome disc's perfect lie, OR to scare aways those rotten disc snatching trees.
Think like a pirate. You want to terrorize your opponent into submission so you don't really have to work all that hard when it comes time to take your prize. A black flag is scary... a black flag with a skull on it is scarier. Same goes for plastic discs.
I was talking about the stamps they use, not the tye-dyes. I agree that they attract new player, and it is because they look cool. I just think that they should at least give a little variety to the way the better plastic looks, the plastic the bought the most by avid players. Its ok to have the plain discs that just says Star whatever or ESP whatever, but throw in some designs too.