It is nothing to do with promoters. It is the venue owners who usually insist on a bar, that is where they earn their money, not with th venue hire. Personally I agree alcohol at all-nighters is slowly ruining them, alcohol usually brings out the worst in people when too much drunk. I prefer the old days when a nighter started at mid-night, you did a warm up at a local soul night and everyone went to the nighter and it was buzzin' from the off, full dance floor etc. But promoters hands are tied.