I expect Disney to be crowded, noisy, and, yes, even to have its share of rudely behaved people at times. And I can accept, say, large family reunion groups heading me off at Haunted Mansion mere seconds before I make it through the chains (curse that search for soap that slowed me down during the bathroom break!)--and grit my teeth when the long lost branch of the family shows up pushing past me to rejoin the ones holding their place just ahead of me. It happens, and I try to set a good example for my daughter about patience and humor (not always successful at that but hey life is a jouney).
I think what bothers me most in any person's or group's behavior is when they are oblivious (or worse, aware but insensitive) to the effect their rude or self-centered behavior has on those around them. So, when it comes to tour groups, it's their sheer size that amplifies the obliviousness and self-ceneteredness to levels that I personally have to avoid in order to maintain my sanity. In my experiences with tour groups before I wised up, that meant squeezing me more and more against the curb outside Fantasmic as I waited trapped in increasingly loud (read, deafening chanting and clapping) crowds for more than an hour, or practically sitting on my lap on a bus back to the hotel (thankfully, my DM, DD and I were among the 9 people who arrived ahead of the tour group--too bad for the dozens of families who got to the stop after them)--but many of you here have much, much worse experiences to relate. I'm just lucky our room wasn't in the same section at the hotel (or worse, I read an account once of someone whose room was in the middle of such a floor and it ended in threatening to call the police).
So now I turn the other way when a tour group is beelining it for the same place I am. I return to my FP 15 minutes later if I can, I find something to kill the time before going to that QS, and I hope to get out of their way fast enough walking down the sidewalk. I even chose AoA because I was betting there would be no tour groups (it paid off, not only no tour groups but we discovered a really charming resort!). They are definitely on my radar and figure in my strategies for every July vacation.
But I think there is such thing as inappropriate behavior, whether it's tour group behavior or out-of-control food/wine behavior, whathaveyou. Disney certainly can come up with rules (I agree, PPs, lots of good ideas here about group size, etc.) and ways to enforce them, to maintain as much magic for as many people as possible. After all, we do come for the magic. Even though we all define it a little differently, there is a zone of common expectations about what that magic is, and in no one's book does that include many of the behaviors described here. I imagine even the tour groups would stop coming if, when they arrived, they were greeted by no one other than tour groups acting as tour groups are wont to do, as far as the eye could see.
And Disney could start with having tours use their own buses to take the groups to and from the parks. (Sorry, pet peeve there.)