Karen Tumulty and Massimo Calabresi hit on an interesting point in the latest issue of Time:
Viewed more cynically, bringing Clinton into the tent could ... put a leash on her globetrotting husband, who has a propensity for foreign policy freelancing.
A lot of people, including me, have been queasy about the prospect of Hillary leveraging Bill's global network in her dealings as secretary of state. But, from Obama's perspective, having Hillary at state may be preferable to the alternative when it comes to handling her husband. If his wife's not the country's top diplomat, Bill will be free to conduct his own shadow foreign policy via the Clinton Foundation, potentially complicating life for the Obama administration. If, on the other hand, Hillary takes the job, there will be strict limits on Bill's foreign activities. Which is to say, maybe putting Hillary in your cabinet is the price you pay for taking Bill out of play.