Why were young Americans so anti-war in the '60s compared to today?
Because they thought Vietnam War was wrong?
Or because they simply loved peace?
Neither.
The real reason was every young male American was required by law to join the military (the draft system) and would therefore likely be sent to fight and possibly killed in Vietnam.
In 1973 US switched from draft system to volunteer system, and since then nobody has to join the military anymore unless he wants to.
That's why today's young Americans and their families aren't bothered by wars anymore. Someone else are going to fight and get killed. So why anti-war?
Whether a war should be fought, whether it's a just or evil war, who kill and who get killed... all these are the last things on their mind.
Sense of justice wasn't there before. It isn't there now either.