Rick Dees had run his course at KIIS, it wasn't really a risk getting rid of him, rather it had become clear to everyone he had to go. And getting rid of K&B or M&B after their 25+ year runs is a less of a risk.
But if you want to man up and put your career on the line, go ahead and take those teams off the air after 10 years of building a loyal audience and start over from scratch. I think that is an excellent strategy for exiting the industry very quickly. In Mark and Brian's case, KLOS was still willing to keep paying them both the big bucks to stay, It was Mark who finally had to put an end to it. In K&B's case, it was Bean who did basically the same thing.
It is a funny thing about money - after you have cashed so many six and seven figure checks, it doesn't have the same motivating effect any more, especially when your job involves getting up at 3:00 in the morning and you are expected to be *entertaining* and generate ratings that will carry the station starting at 6:00. It wears on you, ask any of 'em. And the rule still holds true, the easier the host(s) make it look, the harder the work and preparation it took going in to make it that way.