Do you have a 30" monitor and play games with a 2560 x1600 resolution? Or have you ever experienced playing games like this on another person's computer? Games at this resolution are not pixelated or jagged. Unless you were letting a GPU upscale a game that did not support this resolution the image will look the same as 1920x1080.
I have a 27" iMac (which is the 16:9 2560x1440) and have gamed on it. Depending on the GPU you are running, you may have to scale back on the AA to get decent framerates. At that resolution, I'll grant you that it's harder
to see the pixelation/jaggedness, but that's purely because of the pixel density, not because of the graphics power. That doesn't mean it's not there.
Thirty inch monitors have been out for a while now and plenty of people own them and game with one. So I feel that these state of the art top leading graphic cards should be able to push a game at a resolution of 2560x1600. I remember when graphic cards could barely push a game at the resolutions that were the norm at the time. Since then graphic cards have come a long way and so have monitors. I know that the games have come a long way too. My point is why is a graphics card always behind. The number one card seems like it can never push a certain game to the max, or resolution, or something. You think that it would be able to do anything the most recent game and hardware allow and a decent performance. That is why I am not impressed.
The problem isn't the cards necessarily. Most cards of the last generation have enough raw power to push that resolution without an issue. The problem lies in the pipeline between the GPU and the display, i.e. the card's drivers, the game code, how well optimized the game code is, what features the engine supports and the game is using, etc. Raw resolution with good AA at 2560x1600 is easy for most mid-high end GPUs. However, you throw things in like tesselation, physics, transparency, HDR and other lighting effects and the resources the GPU has available for raw resolution/AA are lowered because of the demands of these other technologies.
I'm not trying to disagree with you - given the choice, I'd game on a 27-30" monitor with all the settings cranked. The reality is that because of these other effects and technologies games use, it's a balance between resolution and image quality, not 100% of both.