Not comparable. Crysis 2 uses the classic "instancing" texturing with using the same texture for different objects over and over again.
The classic approach is more memory efficient at the expense of unique visual appearance and therefore less unique world detail.
Yep. It's a tradeoff. More different pixels to store, more memory space needed, less resolution as a result.
Keep in mind:
Crysis 2 fits on ONE DVD 9,
Rage needs THREE DVD 9s.
For a reason:
Rage has 22 GBs of data. Geometry and engine data is usually rather small so it is valid to assume that most of the data in these 22GBs is texture related.
If you double the horizontal and vertical resolution for a texture you need 4 times the space to store it.
It's absolutely unthinkable at this point in time to release a game that has more than 80 GBs of data.
Neither DVD based storage nor digital distribution would work.
The only way to distrubute it would be on TWO blu ray discs and that would end up being commercial suicide.