Like I said, I don't know much about GPUs so that pretty much made no sense to me. Are you saying if Apple makes the MBP slimmer the graphics will be even less powerful? I want a better card, not a worse one.
Clearly you do need to have little knowledge of GPUs and just a little of physics.
A 6750 has 480 shader cores. If you run it at a higher frequency it consumes more power and produces more heat. If you take a 6970 that is double the shader cores 960. It is effectively double the GPU and consumes about double the power even running on similar frequency, double the heat. That heat has to go somewhere or the GPU will be crispy in no time.
In a thin notebook you have very little space for cooling fins and fans. An gaming notebooks are usually huge with more space in all directions and fans inside that can move 10 times as much air per minute as the meager MBP fans.
I just meant to say money has nothing to do with how fast a GPU you can stuff into such a notebook. You want gaming power get a big gaming notebook or better yet a desktop PC. Desktop grade GPUs need all by themselves about twice the power as the entire MBP combined. They get quite a bit of extra speed out of all that power too.
If Wikipedia is to be believed, the 7750M is considerably faster than the 6750M. 832 cores up from 512, at similar clocks. Would make it more in line with an overclocked 6850M.