In the past 10 years we've seen significant development in games, especially when it comes to graphics. The level of detail in games like CoD4 is just awesome and really adds something to the overall singleplayer experience.
But concerning the state of hardware we have today, it's not that impressive anymore at all. It seems to me like todays developers avoid the real challenges - they just rely on directX features and the newest GFX cards, but dont really invent something new.

If you compare the development and improvement of GFX to the AI we have today, it almost seems like coders stood still and just picked up what hardware-companies threw at them.
CoD4 is a perfect example: Besides enemys throwing back grenades, they'r just as stupid as in CoD1 or any other random shooter. The whole tension is based on masses and masses of enemies, so that you won't even recognize a single stupid bot because theres so many of them. I still enjoyed the game though..

Maybe it's just a matter of time until some sort of hardware AI-accelerator comes out. But imo it's really sad that improvement in games seems like its only based on what newest hardware has to offer.