It has been a very, very tough four years and my sense is that a number of Cabinet members would like to get on with their lives in less stressful and/or more lucrative jobs. Think of what these guys and gals have gone through; makes your basic merger or business reorg look like a walk in the park. If I were Powell, Rumsfeld, or Ashcroft, I'd probably be looking for a new gig as well. They've done their duty and deserve both our thanks and the opportunity to de-stress and make some serious bank.
That's essentially what the President said in his presser today--that people burn out. He called it "a great Washington sport to speculate on who's in and who's out."
I think you have a good point. Lucrative jobs come to staffers and cabinet members after the first term....not after the second term. THEY ALL KNOW THIS. Those who are looking for financial gain will leave now. Look back over the last twenty years you'll find proof.