Again, thanks to all who responded to my query about the switch from reviling military people to honoring them.
A couple of more came in after the original posting, so including those below.

Hoosierland

  I think there is another thing that might play into the present day honoring of vets.  Our country likes get all hyped up about whatever is the latest craze.... tons of flowers at the site of a shooting, vigils on anniversaries, gatherings for causes, etc, etc.  With the media 24/7 and social media bringing instant gatherings, I think a combination of:    a) a determination not to repeat the poor treatment of the Vietnam vets .  Because the war was so hated by the young, the treatment of the men fighting was part of the disdain b) an environment of loving to show caring and appreciation for whatever...  c) a politically correct environment that says our military should be honored even if we don't agree with the war  d) politicians over the past 10 years touting their service even if it was minimal...    It has become the politically correct thing to do and when that is the case, stand aside......

Colorado Vet

   My 2 cents worth.  I believe a strong contributing factor was the Vietnam vets, and perhaps their children, who saw the troops coming home from Iraq and Afghanistan.  They said to themselves: "Even though no one said 'Thanks for serving' when we came home, we're going to make sure that doesn't happen to these men and women."  Sort of a "Do unto others as you wish they had done unto you."  It began in small ways in various places and caught on because people saw it was a good thing to do, the right thing to do.

       By the way, you and I both went through Basic Training at Ft. Ord.  Sun and sand on the rifle range!  And rain, lots of rain.