Mary --
Here's the big dilemma for parents (and trust me, you will see this when you have kids because it used to drive me NUTS when my kids were young): what do you do about the people who flagrantly break all the rules?
I always made sure my kids never climbed fences, cut in line, pushed or shoved, or did other bad things. But sure enough, wherever we went, I'd see other people let their kids do all those things. Sometimes my son, especially, would push and push and push me to let him do things he saw other kids doing. I heard a lot of "It's not fair! That boy's doing it!".
Personally, I just think Imagineers need to see things more black and white, with only two options available:
1. Whatever you are building is meant to be climbed on and is safe for kids
2. Whatever you are building is designed so that there's no way a child will see it as fun to climb on
Casey was built NOT to be climbed on but was made to look like the most fun thing in the world for a child to climb on, so it was a real failure in planning for WDI. Someone should have assumed that kids would see it and want to climb it and that a mere railing would not be any disincentive to climbing for bad parents who allow their kids to do as they please.