I thought about the point you were making in your second paragraph. The only thing I could think is that is where ego and feelings come in. If he were to stay, there would be the constant reminder that BG was chosen over him, or he might disagree on decisions, but not want to cause problems. So, the change of scenery gets you away from that, even if the job you are moving on to isn't any more highly regarded.
The other reason to leave is to be a part of building something. Oakland is further along than Cleveland (duh) in their development as a franchise, but nobody has seen Oakland be a consistent power. If Wolf goes to one of those places and they become consistently good, then he is even more of a hot commodity as a GM candidate.
Also, John Dorsey and Reggie McKenzie are much older than BG, and closer to retirement, so Wolf's wait in those two places wouldn't be as long, provided neither or both teams remain/become a dumpster fire and everyone gets fired. That's the risk if you are Wolf. Stay with the established Packers, who are having a momentary changing of the guard, or go to two places that are trying to establish a winning culture.