It is more economically reasonable ($$$), reasonable, feasible, and sensible (Thats a lot of -ible!) to have non themed uniforms. Not too mention, cheaper on a wide scale basis! And paramount is about cutting costs to get more of a profit, without cutting safety and quality, really.
They also play well in the whole ranking business, so a guest can tell a supervisor, an associate and a manager. Personally, I have never worked at PKI with the themed uniforms, although I remember them well from my season pass days...
Like other things, I like the idea in theory, but in practive it isn't as grand as one would think it would be.
I think the unity and uniformity (haha) of the uniforms are excellent, and they look professional, even if I don't particularly care for the new ones with the stars. Now if we could get them to update the blue pullover, and give back the raincoats.