You are all wrong IMO
It's not about a draft
It's about the death of journalism and partisan controlled mainstream media.
Most opposition from the war were from democrats, and MSNBC never talks about any of the wars.
that's why they fired Phil Donahue, even CNN is guilty
Media is much more polarized and given into outside interests today. Plus the Fairness Doctrine being killed.
When Walter Cronkite told America that the Vietnam War was not a winnable war, they believed him, and that fed into how the war ended.
Agree with a lot of whats already been said but i'll add that the "Thank you for your service" and military hero-worship culture that sprung up as a result of Vietnam has also played a big role.
I recall reading that soldiers coming back from the war were told to change into civilian clothes before leaving the base for their homes or the airport or bus station, such was the antipathy towards Vietnam vets at the time.
I can definitely see today's veneration for the military as a reaction to that.