I'm all for a retina display, but I'll play devil's advocate.
A retina display of 2880x1800 will make everything sharper, yes. But it also means your graphics processor must push 4x the number of pixels. It's an equivalent of plugging in 3 extra 1440x900 monitors to your MBP.
Crystal-sharp games sound good right? But what if it runs at 7fps because your GPU has to work 4x as hard? Not that fun, is it?
Or one could also think of the non-gaming aspects. 3D rendering programs like Maya rely heavily on the GPU, and occasionally lag on the current 1440x900 screen. With a high resolution display it will bog down performance of the program.
Even with GPU improvements, it won't change the fact that the GPU has to work harder.
Which leads to a heat issue. A hardworking GPU creates a lot of heat, which means a retina display will cause your laptop to run at high temperatures much more often. A hardworking GPU also draws a lot of power, which, along with the brighter backlighting necessary for the retina display, should greatly decrease battery life.