Originally Posted by PAXboy
When the 741 entered service, most carriers used the upper deck as a small smoking room, with lounge seats.
I believe (but confirmation from crew would help) that early 747s were not permitted to use the upper deck for take-off/landing due to evacuation difficulties. This area was then available for in-flight luxuries (including bar with piano). Later models had escape chute long enough an thus the area became available for revenue. The same would be true for the lowest (non-PAX) deck of the A380