Its a business. However, wouldn't anyone feel somewhat uncomfortable when the first thing the new boss does is try to get rid of you? How do you trust him after that? Then after that saga ends, he gives no assurance of long term predictability.
Yeah these guys make millions, but it sucks if you have to move or uproot a family every couple of years - and not knowing when that could happen puts undue stress on you. Football is a team sport more than any other, and trust and familiarity breed success. As a QB, trust is huge. You have to trust the O-Line to block for you, the receivers to be at the right spot at the right time, etc, etc.
AZ54 is on to something. There is no way Cutler is traded if the owner was not in on it from the start. He knew about McDaniels idea, and they felt so strongly about it, they got rid of Cutler anyway. Plan B.