I sailed on Diamond when they had open bar back in 2003. There were no in-room set ups. I went down to gift shop and bought bottle of scotch for $15. Our friends, on the other hand, just called room service each time they wanted a drink in their room. I would think that this can become a big burden on room service thus my supposition about the bottles.

As for the policy change, there are still people that don't realize that you can get free drinks in dining room at dinner. There are many of us that top off our drinks prior to leaving dining room. This was an unadvertised benefit that cut down a bit on alcohol consumption in dining room. I think not putting in the bottles in room unless asked would be a similar situation.