As we progress into a real-life counter part of us but in the fashion of total realism on our computer screens, there are a number of things which people must trade off in order to obtain the new limits in computer graphics.
Wheel back a decade and people were wooed with the 32-bit image, a few years before that, it was 24-bit, but it was just picture quality not in gaming. Around that period was the Playstation period with the 8bit 3D games such as Final Fantasy VII (later with 24-bit graphic games) whilst Half Life went to 16-bit, focusing on future tech. Both of which were very big and significant title for the period. Playstation was constricted to the 320*240 (640*480 max) screen size whilst half life was 640*480 (1024*768 max), but that was due to restrictions in processor power in the system at the time. Now, the screen resolutions must be 1920*1680 to catch every single detail and to make sure that you can account for every single moving pixel to make sure that you don't give away an advantage to someone, mainly from Counter-strike.
Thing with these modern games is that they take so long just to produce, then creates extra work to everyone in the team not just for the 3D modellers and map designers, so then comes down to everyone else to pull the chain to keep up and make sure that they don't fall behind production schedules as 3D modelling takes a good majority of time. Then, the programmers have to make sure that there are a range of conditions and parameters which the game must perform under and double check for 3D modelling glitches, push the production back more.
As games attempts to break through the barrier of perfect gaming graphics, there's the hitch of noticing with problems within the 3D model such as lips, weight in objects, eyes, model clipping issues and so on, they reach the area in graphics commonly known as the "Uncanny Valley". There are some games which have reached to the stage where models are far too farfetched to be believable in real life. Take a quick look at Crackdown. Plain looking ordinary character with super extraordinary skills later on such as ginormous leaps of faiths and learning how to make weapons do more damage. Make prob would have to the look of the character in terms of the face, hair, facial hair and so on. Knowing about quick shortcuts to hide problems, there will be small hard to notice problems within the game and you'll see them sooner or later.
Now with games only being accepted only if it has really good graphics, such as Gears of War, Call of Duty 4, Crysis and Bioshock. Those games do look good and have gone beyond the normal conventions of the limits within graphics and processing power on their respective systems, there are many games which don't recieve such a high score but requires other areas in review to compensate for it, which are sound and gameplay. Take Super Mario Galaxy for instance, the game's graphics were rated lower than the modern games, but its overall performance as a game matches or better its rivals.
Later in the future, maybe 5 years down the track, people will look back on the "pretty" games of this era and look down on them and call them horrid. That's the ever growing bar of perfection in the graphics business.