Especially when many bluray discs are mpeg instead of h.264, and supposedly quite a few discs are at a bit rate that is overkill - it sounds like they're filling up the disks just because they can.
Blu-ray uses MPEG-2 and H.264/AVC. A 10-bit "uncompressed" 720 24fps 2 hour film clocks in at around 400GB. A 1080 project (which is what many people are shooting on now) can clock in around 900GB. That's the size of the final master file in those formats, as perfect as they're going to look. Now those pixels get crunched down to 25GB for an HD optical disk. For AppleTV they get crunched down to 2GB (? still not sure exactly). Trust me, there's no overkill. Even a Blu-ray disk does not compare to the original. Post facilities should offer guided tours so that people can sit in a finishing suite and see what a true HD signal on a $25,000 professional monitor looks like. It is truly amazing. Go to NAB and check out some demos. It makes your HBO HD look like VHS.