I haven't seen this fine movie in 50 years but I'm entering a comment on it anyway.
While JACK WEBB'S movie was no doubt intended purely as an entertainment --- showing Marine basic training at Parris Island in realistic terms as a tough character-building exercise -- it was said the military was afraid the movie would discourage recruitment's. It did not work out that way. The movie showed that entering the Marines was a greater challenge than most young people ever realized, and (guess what?) being offered a king-sized challenge was exactly what many guys wanted. I personally knew lots of guys that joined the Marines shortly after seeing THE DI. Lines at recruitment centers were suddenly so long the Marines had more recruits than they could handle.
So it goes. America will always have youth seeking to make themselves into the best --- while the slackers and born-losers limp along to nowhere.
What we DON'T have in 2007 is any films that inspire patriotism, devotion to duty of any kind, positive values, et cetera. What we DO have is films that inspire the airhead-ed to be airheads, the beer drinkers to guzzle beer, other negative values. Exhibit #1 is that the airhead teen travesty and beer guzzling epic SUPERBAD is now #81 in the All Time Great Films list. Values? What'cha mean, values?