@RackMaster I think the issues are significant.
1. If we're saying Soldiers should be eligible to drink before citizens I think we're sending a terrible message to the military and civilian world. Of all the privileges and rights you could honor service with early alcohol consumption seems like it should be very low on the list. The message elevates the importance of alcohol consumption - something society already struggles with. Further, the rates of alcohol problems - especially when mixed with prescription drugs - amongst service members are significant.
2. If the rules are intended to make the lives of Soldiers better or safer we have concrete examples where it has been tried - and it did not work. I was at Ft. Huachuca for the MI Captain's Career Course in 2007 and they were trying it out - it was a disaster. The idea was Soldiers were going to drink anyway, why not give them a controlled environment within walking distance of their barracks thus cutting down on DUIs, unwillingness to report serious incidents for fear of getting in trouble for underage drinking, and the victimization of Soldiers by predators in the surrounding area. The results were a significant increase in binge drinking - after all, the post commander has essentially endorsed alcohol as the best means of having fun for young Soldiers. With the underage drinking allowances you now had a flood of underage civilians flowing onto post as 'guests' in order to partake in the festivities. Soldiers were able to hook up with a lot more high-schoolers with the new policy - and the post got to deal with all the consequences of that to include statutory rape, contributing to the delinquency of a minor, etc. Article 15s went through the roof as Soldiers could now drink as much as they wanted - alongside their cadre - then walk over to the barracks and get into it.
Drinking, like many other drugs, is a personal right and responsibility. Whenever it becomes a significant part of the identity or social structure of an organization it becomes a problem. Army policy, in my opinion, should be similar to every other off-duty activity. Have fun as far as the law and your own morals dictate but you are always a Soldier and always a leader - so the Army Values and your responsibilities never cease, no matter what you put into your body.