I would highly recommend not using them if you haven't used them in other water parks. I can't stand them personally, would never wear them. Yes, the pavement can get hot in some spots in the park, but they do a decent job of watering down the walkways, so not all of the pavement is hot. The lines for the slides are never hot, as they're almost always wet. It's just the walkways to get from one part of the park to another that can get hot. I just hate walking around in wet shoes of any kind...nasty.
I think it's really a personal decision on if you like water shoes as a concept. If you do, wear them. If you don't, then don't, you definitely don't "need" them.