When Apple made Xcode into its own app bundle it greatly simplified our lives as developers. This enabled incremental updates for the stable version can get from the app store. Also you get updates the same way as updates for other apps.To cut down on file size Apple made several items optional downloads, like the documentation, older versions of Simulator or Command Line Tools. The latter you need if you are building stuff outside of Xcode, like Open Source projects. You know, bare knuckles, command line geekery.However those tools are not needed if you want to say use svn or git. This article explains why.
via You Don’t Need The Xcode “Command Line Tools” | Cocoanetics.