The US abolishment of the draft in 1973 was of course a result of Vietnam, but also rested on another, organizational logic. Namely, that the potential for a more professional Army was higher with an all-volunteer model. This perspective, moreover, fitted absolutely nicely with the transformation agenda of the 1990s: the vision called for far fewer men, empowered through more gadgets and technology. The UN peacekeeping missions (and other MOOTW/contingency operations) which exploded during the decade seemed very old-fashioned compared to this.
The post-9/11 situation, however, has shown how close the challenges in Iraq and Afghanistan are to the PKOs: operations that are political in nature, dealing with the local populace to gain its trust, calls for a large footprint in terms of manpower. So the draft is back on the agenda -- for lack of men -- as proposed today by Rep. Charles Rangel.
A reinstatement of the draft, more than merely provide manpower, could probably change elements of the relationship between the Pentagon and the general population in the States. The oft-mentioned socio-economic bias in the self-selected troops would decrease and the Army would start looking a bit more like the rest of the population. And having more drafted middle-class pfcs would likely bring with an increased form of attention, which might be healthy. But the spectre of these changes is also the reason why the draft will have a hard time returning -- in spite of the need.