There was no reason for this to even get to a point where physically removing a passenger who did nothing wrong was necessary. There was a very simple solution

There was no reason for this to even get to a point where physically removing a passenger who did nothing wrong was necessary. There was a very simple solution here: United wanted 4 seats, offered some vouchers, and got no takers. At that point, you start sweetening the deal for giving up your seat until you get some takers. I guarantee it wouldn't have taken much.