Precalculated lighting requires tedious compilation times for each level, running raytracing or photon mapping based GI calculations with high precision and all. Back in the Quake days id used to have some serious computing power with SGI servers in the basement to speed up level design iterations. I imagine they've had to build a new farm again for Rage and Doom4.
Then again, Crytek's GI system probably requires some amount of precomputed info too, I'd guess, but it's still less extensive. You can change textures and shaders and watch the results in at least near-realtime speeds, instead of having to wait a day to notice that the new floor texture makes everything in the room look yellow or so.
