1. It would prevent, or make more politically difficult, resort to wars that are bad choices, such as (according to Ricks) Iraq.
Secondary reason, Sanka-fied:
2. It would connect and engage the civilian population with the lives of servicemen, making them more aware of their travails.
(2) would support (1).
He compares Vietnam era social/political fallout, with Iraq War era fallout, and comes to this curious conclusion:
Resuming conscription is the best way to reconnect the people with the armed services. Yes, reestablishing a draft, with all its Vietnam-era connotations, would cause problems for the military, but those could never be as painful and expensive as fighting an unnecessary war in Iraq for almost nine years.
This just seems demonstrably false. Comparing the "pain" and "expense" in dollars constant, I suspect that the Vietnam war was the more 'expensive'. Having no numbers in front of me, I admit this is a guess. The Vietnam war certainly saw more carnage, pain and suffering. Its aftermath was bloody, ask the Vietnamese and Cambodians. But, keeping focus on the U.S. military, the effects were not good. The public perception of the military suffered, and the instutions suffered a crisis in confidence. The general social upheaval needs no belaboring.
The 'unnecessary' Iraq war had far fewer casualties for U.S. forces, fewer Iraqi casualties, and did not cause the same sort of upheaval and loss of confidence, even if there was an anti-war movement.
Having said all that; the draft was in place back in the 60s, and that 'unnecessary' war occured anyway, dragging on for years with all its negative, as did the Iraq war sans draft.
So, how is the reinstatement of the draft NOW going to fundamentally change things?