By the time you have "earned" the 1500 points required to get the "free" drinks, you have spent more than you could have possibly drank buying them straight from the bar. And as Dwayne pointed out, once you get to that level you still have to be playing in order to get the drinks... so more money.
Las Vegas and other casinos learned a long time ago that if they offered free drinks that people would stay at the casinos longer and drink more in then in time spend more... Its the same game here, but why the 1500 point level I don't know. i would bet that they have been hearing the complaints about not offering free drinks that they figured this would appease the serious gamblers while they would not lose money on the people coming in and playing a little money just to get a drink. I do think the 1500 point level is way too high but then they have a caged customer... where else are you going to go?
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007