Yes I know they must be quick - I have a cutting bred gelding and he is very quick but not as quick or as aggressive as the WB. What you have to realize is that WBs were bred for the military to be be big, strong, and aggressive. AQHAs were bred to work on ranches to be calm, smart, and submissive.
I think a lot of horses can be difficult in the wrong hands but my WB would be difficult in "most" hands because most people don't have enough savvy to handle a horse like that. I guess it's just one of those things that cannot be appreciated unless you see if for yourself.