By default (IIRC) Visual Studio installs a dozen or two other items along with itself. Each of these have to be uninstalled separately if you want to actually get completely back to the state the machine was in prior and you can't use restore points.
It's nothing new (this machine has only 2010, and a quick check shows seventeen separate uninstallers that would have to be run to get rid of all the libraries, SDKs, SQL compact/express, etc.), but most people never need to uninstall, or at least don't need to uninstall .NET itself. That's the main problem, since if I remember right all the other stuff is registered as dependent so it all has to come off first to revert the framework (and yes, MS has gotten flak about the whole in-place replacement of 4.0 with 4.5).