They already had the policy, but it was limited to lockerrooms which made the policy a joke. You either implement it right or don't implement it at all, so changing it either way in my opinion is better than keeping a laughable restriction in place.
Now, if you read that extended article, this was approved by the Players Association and an advisory committee made up of veterans. Apparently, the players want this, at least the majority does, so I don't see the issue.
Oh yeah, and I could probably get away with having a beer during lunch, but I don't even need to ask in my field, if I'm ever buzzed on the job, I'd get canned. Its simply not acting as a professional, so I have problem with any company really saying "No alcohol while you're representing the company."