The current punishment isn't really enough, in my opinion. The CO hands out pretty much the max punishment every single time, but a lot of these guys end up back in the pipeline, minus 30-45 days and their crows. It's not even really an integrity issue (though after attending integrity briefs done by the A-DOS, CO, DSED, and the P-DOS I think, I'm not really sure what the official definition of integrity is anymore), it's more of a "how stupid are you" issue in my eyes.
You WILL get told over 100 times in your first week to not underage drink. Every indoc brief mentions it at least once, your indoc SLPOs will re-iterate it every 10 minutes, and most other students (myself included) will tell you to not underage drink. It's probably the first thing anyone tells an indoc when they talk to one, because it's that big of a deal. Words can't really express how much you will be hammered with the phrase "don't drink underage" in your first week alone.
And yet, at least one person goes to Mast for it at a minimum of every other week. There was an open mast of about 2/3rds of a section a couple weeks ago, all for underage drinking (and one kid who broke in to another guy's house to steal beer). Mildiv travels as an element now, and the only reason it's not huge is because they have no more berthings (or so I've been told), so a lot of these dirtbags got DTP and CCU. It's really an issue of "can you follow instructions" more than anything else in this case, because if you can't be trusted to not underage drink after being told hundreds of times to not do so, how can you be trusted to follow procedure on watch, not blaze logs, etc.
Underage drinking in particular should be grounds for immediate dismissal from the program, no if-ands-or-buts about it. It's completely inexcusable.
Jus Me: They do have someone who's been masted for underage drinking talk to all the new arrivals (at least they did when I got here), but I don't know how effective it is, really... It comes so late in the briefing schedule that by that point if you haven't decided to not so much as think about alcohol until you're 21, you're just plain stupid.