I don't agree. Controversial as the wars of the last decade or so have been, they didn't divide the American nation as much as Vietnam did. And, for the most part, the actual troops fighting in Iraq or Afghanistan were not criticised as much as the leadership (though I've read that the stories of soldiers returning from Vietnam to be spat on or have blood thrown on them were exaggerated anyway). Having said that, there are sadly many veterans of the last decade suffering from PTSD and the like and I'm not seeking to downplay what they may have undergone.
Also, in writing Rambo, David Morrell was putting together the hostility to veterans with the hostility to the counterculture and hippies; Rambo looked like a hippy in FB, not a military man, and this in part annoyed the small-town sheriff in that story. I don't think that there's quite the same schism or coming together of factors today as there was at the time that Morrell wrote First Blood.
Then again, a TV network might be quite happy just to have the character of a tough but traumatised green beret war veteran and 'update him for a new generation', so what do I know?!