Perhaps this has been mentioned before, but in this interview is the first time I've seen it:
We also separated movement from combat speed [in Fallen Enchantress]. In the old system if a unit had 6 combat speed he could move 6 spaces, attack 6 times or a combination of the two. That made combat speed a god stat, since allowing more attacks multiplys a units damage. Now we can have high movement units without making them killing machines (or make really slow killing machines).
Now that has been a long time coming. Maybe not the flashiest or most exciting change, but it's one of those basic mechanics WoM needed - very glad to see it in FE.