They probably did it to make sure people actually had enough RAM for a game that was copy and pasted from the Xbox One. If the game itself uses 3GB, that doesn't leave much RAM left for Windows if you only have say 4GB of RAM. In any case with the new console generation hitting now if you only have 4GB of RAN, you really do need to upgrade as the new consoles have 8GB, and at least 5GB is likely to be useable by the games once you subtract out OS overhead and graphics memory requirements. If you are still on Windows XP or have a 32 bit version of Vista or newer, you'll need to upgrade to a 64 bit OS to be able to address all that RAM.