Oh my goodness - young Royal in drunken, naked revelry shocker!! 
Wow, this sort of thing has absolute no precedence at all - this must be the first time such a thing has ever occurred, like ever, in the history of royalty!! Shame on Harry for bringing the fine lineage into such disrepute! 
The only difference between nowadays' royal revellers and the multitude of royal revellers past is this existence of the tabloids, press, Internet and social networking. It's a hell of a lot harder for our guys to get away with stuff than it was for the court of King Henry VIII and his guys... 
As for those of you who were all grown-up and straight-laced, tied down with responsibilities and No More Fun at 28, well, unlucky you. Personally, I was still revelling well into my 30s, and take any opportunity even now for a night out of revelling, if it's offered my way. Sadly too few and far between these days.
Life is short - if you choose to settle down early and spend the rest of your days in mundane responsibility, fine. But don't be surprised that others may want to eek out their enjoyment for a little longer. You're a long time dead. You may think you're officially better than those people, but, well...
And as for those naive enough to think that a spot of naked billiardry makes him unfit for service - well, you're obviously very in the dark about what many military types get up to during their R&R.
The only thing that winds me up about this whole non-event is as the OP says - the complete and utter double-standard that would be at play, had this been a woman royal instead of a man.