I don't care about discs. The problem is that, assuming they're having one data disc and one play disc, they are forcing people to install an obscene and unnecessary amount of data, which is the same problem as large day-one patches. It's especially bad for people who download it digitally because the game's gonna take up 80gb when it really shouldn't. Launch PS4s and XBones only have 500gb hard drives.
Rockstar doesn't have a great track record with compression either (there is no reason GTAV had to be 60gb+ at launch, for example).