Bruce,
I enlisted in 1977 when the Vietnam-era "Joined the Corps instead of going to jail" personnal were still being thinned out.
I do not think the Corps cut back on it's values after Vietnam but it did suffer in losing funding! Lacking a war and the ability of the Gunny to beat the heck out of a troublemaker legal discipline was ineffective. Times would however soon change!
Later in my career I served under Major General Leslie Palm,
http://en.wikipedia.org/wiki/Leslie_M._Palm General Palm told of interesting times in Vietnam and of the post-war period. The Officer Corps of the time decided enough was enough and the trash had to go. Over the decade of the 1980 the Corps tightened up and we all stood more proudly. Those pieces of shxx were flushed down the tiolet by General Palm and the officers of his era.
The Marines of today are much like fables of the knights of old. Firm, good mannered men and women who will cut out your tough if you speak ill of the Corps and fellow Marines. Kind of gives you a comforting feeling, doesn't it?