I think there is a kernel of truth to what you are saying, but I also think it is unfair to compare the kids who were sent to fight in Iraq War, Gulf War 2, Vietnam, et al. to fighting against Hitler.
The argument can be made that fighting Hitler literally was fighting for freedom and the soul of western liberal democracy. Hitler was a unique and dangerous threat. The type of threat that only comes around once in a millenia. Ghegis Khan was probably the last threat on the scale of Hitler.
Fighting to defend the Kuwait royal family in Gulf War, 1, getting involved in a civil war in Vietnam, or invading Iraq under false pretenses were not "fighting for freedom". They certainly were not comparable to the type of threat Hitler represented. And I doubt that anyone who really thought that those Middle Eastern and southeast Asian conflicts were really the kind of existential threat worth American dying for.