That's the problem with the entire GWOT in my limited opinion - we're still operating off a large set of faulty assumptions.

The senior military and political leadership never wanted a larger struggle - hence the President's referral to continue shopping rather than a call for military or civil service after 9/11. They believed the volunteer military could defeat any threat. There was never any real thought of expanding the ground forces...and that opens the question of "why not?"

When a war of choice is started (Iraq) and things start to go bad, and the rationale for fighting shifts and is rendered null and void, one cannot expect a call to service to work. Even if the assumptions are changed now, I suspect the only way to successfully expand the military at this moment would be through a draft (and that equals political seppukku) or through a massive terrorist attack, larger than 9/11, on American soil.

Timing, as they say, is everything.