And yes, when the man refused to get off the United plane, he should not have been beaten. Big deal, hundreds of millions of people fly every year. The fact that that happened sucks, but the reality is that 99.99% of people will at worst just deal with incompetent customer service during a cancelled or heavily delayed flight. That doesn't give you justification to steal from the airliner.
This is a discussion I feel you would have with a teenager.
Though, to be a bit more generous, I'd interpret that people hate airlines without really having a conscious reason, so they make something up that's visible and easy to be upset about. E.g. Cost of flying, leg-room, crappy service, "run by evil corporation". I'd posit that they somehow see something wrong with it, yet can't pin-point what that is. In my view, somehow they realize that a government-enabled and enforced monopoly makes the whole thing unfair. And if only we had no intervention and prevention of competition, they'd finally see "nice" airlines. But until they actively "see" that, they'll always think that it's the government that's preventing the really nice peachy happy people from running an airline that they'd enjoy using.
Edit: sorry, this was kind of a flippant remark that I made without thinking a lot.