[mathattack]

Exactly. By this point it's out of necessity, to stay in the game. It's like asking an MBA, "If you could get to a plum Wall Street job without an internship, would you?" All of them would say, "Of course not!" In Science, the supply/demand imbalance is such that this "internship" (post-doc) lasts a lot more than a summer.

I have a friend who did his MD/Phd immediately after undergrad. That wasn't enough to land a job, so he did a several year post-doc before landing at a research university. Even still he was in his 40s before getting tenure. At that point tenure is about rewarding performance more than anything related to academic freedom.