I wouldn't worry or get involved in it.....
My 7 year old niece freaked out about the Haunted Mansion, tears, sobbing, clinging etc. She loved it when she got off....same story with Space Mountain, Dinosaur and a few others. People probably thought we were horrible for dragging her on, but she enjoyed every single one.
The only ones she didn't like that we forced her on were ToT (but she was so proud she tried it), Snow White (have NO idea what the problem was with this one) and Pirates (again, not sure what the problem was).
Each kid and situation is different. I am a big believer in the parents (guardian) making the decision for their children. I also believe that many kids are too coddled, and their parents allow their fears to get the best of things. My motto with my niece was, try everything once, and if you don't like it fine, don't do it again. But how will you know until you try.....