>but legally you have agreed to follow the license //

I'd say "are bound by the license" - however if you download Xcode from the app store do you get "adequate notice" of the browse-wrap license?

Can't personally inspect the license from https://itunes.apple.com/WebObjects/MZStore.woa/wa/viewEula?... as it redirects saying one needs the Mac App Store to do that.

A license can restrict use, but copyright concerns copying. They allow copying of the code, which is necessary for use, but attempt to acquire acquiescence to their license terms. I'm not sure however as there is no consideration how users can be considered to be under license. In short if the copying is fair-use, which it looks like it reasonably could be, then how can the use be controlled?