so rage will be 22 gb to install on the xbox but the system requirements to install skyrim onto a pc is 15 gb. rage is said to have 500 animations per character model that will use up a lot of the 22 gb. so why does skyrim not have the same sort of size of a game when its supposed to be so in depth with things to do for hundreds of hours?
Because RAGE have a http://en.wikipedia.org/wiki/MegaTexture#Virtual_texturing for the whole game world, while Skyrim do not.
Also, using the plug-in system, the actual game world data take a relatively small amount of space compared to most other games. If Skyrim was built using the Id Tech 5 engine or the Unreal 3 engine or whatever, I'm certain the game would take up a lot more space because the plug-in system isn't there.