We've always worn the water shoes at the parks, but for a different reason.
We went to our local water park, which is really a nice, clean park, one summer years ago. That October my daughter developed a wart on her toe. I took her to the doctor and the first thing she asked, did you go to Splish Splash this summer? I said, yes. She said there are always kids coming into the office during the beginning of the fall with warts on their feet. She said it takes a few months for the wart to develop and that she was probably infected at the water park. We did not wear water shoes then. The doctor said that we should always wear the water shoes whenever walking around a place like that.
So that's the reason we wear water shoes at the park.
Believe me, those things are just soooo unfashionable! But I don't want to get warts (or any other skin affliction involving the feet!)