I know exactly what you mean. I haven't bought another Call of Duty game because none of them are good as COD4. I only own Black Ops because it was free. I miss those days of playing COD4 with my friends. Where did the time go???
I heard fourzerotwo (Robert Bowling from IW) saying they want to go back to the COD4 roots with MW3. Let's see how it turns out. But just like you, I really miss those times. The key was definitely the smaller maps. Maps like showdown, Crossfire or Crash were perfect. let's hope MW3 has more of that. I hate the new trend introduced by MW2 and black ops were you actually spend more time after spawning running back to where the action is happening, that actually shooting people, only to be taken down by a sniper camping in the woods (I'm looking at you: Derailed and wasteland). I want to go back to urban firefighting. Shooting in cities is awesome. A fuckin giant field where it actually looks like you're playing Oblivion, WoW or some MMORPG, not so much.