So you wouldn't mind someone toying with your vacation and you can't do a thing about it? I think that is more of what is bothering people than anything else.
What if you saved for years for this once in a lifetime vacation(which isn't cheap) and now you have very little control over it?
... I do have control over it. No one is forced to use any kind of fast pass + or - the rides are all there without it and a good time can be had without using the fast pass system at all.
When anyone buys tickets to a theme park they're paying for admission. Not a guarantee of fast passes or anything similar, they bought admission. If they toy with me getting into the parks I might have an issue with it, but as long as they offer what they sold (admission) then I don't see it as abhorrent an act as some posters seem to.
What parts of the vacation are you not in control of?