they dont push for speed because its a bit of a wall. Intel will continue to make their tick-tock kind of manufacturing, its working very well so far. tick-tock is where intel releases say a 65nm processor, then next year they revise it with new 65nm processors. this is the tick, then the tock. now we hit the tick with the 45nm cores, and the tock is the i7's.
this is working well enough, why are people constantly asking why we're not pushing for speed any more? i dont care how fast you get it going, a P4 will never ever beat a dual core.