Oh sorry, didn't realize that 3GB was the absolute minimum frame buffer for a proper e-peen this time around.
The vast majority of users in this market use monitors with resolutions of 1920 x 1200 or below where 2GB is pretty much unnecessary. AMD is charging for 3GB of RAM which most users have no need for. If you're happy paying for things you won't use then be my guest and shun Nvidia for finding 3GB as a standard framebuffer a bit unnecessary.
Not everyone is going to spring for a $500 monitor, at least not enough to warrant a necessary 3GB of memory. Also this model will probably have a 4GB variant sometime down the road so that all you VRAM connoisseurs can be appeased.