I just got back from Hawaii with the family and flew both directions on a 757. Both seemed a bit older but appeared to have updated overheads. Both aircraft had no gasper vents at all. The cabin seemed to stay fairly comfortable but I was surprised to see that change. I admittedly ride in the back of 75's very infrequently so this has probably been this way for some time. My question is are all 757's being retrofitted to remove eyeball vents and if so why? Extra bin space?

Thanks