Head tracking, foot-planting, and refs where all done a while ago. Nobody really clamored for 3-d grass. Madden started off on a poor foundation that has never been fixed, and due to the lack of competition, EA has no incentive to really get into the core of the game to correct the faulty foundation. If they are, they're certainly taking their good old time doing it.
This notion that only so much can be done in one cycle is a bunch of crap ! Eventually Madden won't be the only football game in town. When that happens, whatever year (or decade) it is, watch how much Madden improves. Watch all of the legacy issues vanish into thin air in one cycle. Watch Madden catch right up with the rest of the sports genre. Now I'm saying that there won't be issues, but those issues won't be the same issues popping up year after year.
That being said, I am enjoying the M12 demo. I've played it more than any other demo that I remember, but Madden is still behind the other sport titles. That's a fact.