I've been told that there isn't actually a policy banning caffeine. Someone made that decision at one point, but it was never codified, so it's more of a tradition at this point.
So, what Carrie Jenkins was talking about was demand from departments. Everybody is afraid to be the first to buck the de facto policy, so nobody has ever asked the administration if they can do it.
Honestly, I wouldn't mind a change in the policy, but I don't expect it to happen any time soon.