Aren't advertised academic positions basically saying, "We can't find anyone who wants to work for me unbidden?" Is there anything wrong with that? Assistant professors and such gotta start somewhere, right?
So it might be good for the professor to get experienced hands in the lab. Is it good for the postdoc? I'm not so sure. Even if they manage to do awesome science (and of course, they will), will their employer have the influence to get their postdoc a good next position?
Readers, what say you?