The 5D MK II was aimed at wedding photography, not action or sports. Those who wanted it to be something else, were disappointed. The camera has so many other good attributes, that if Canon were to put in a more sophisticated autofocus system, it would have undermined 1D/1DS MK III sales, so Canon did not.
Its no different than holding back high end features in a automobile that is targeted to the low or middle price range, manufacturers want you to buy the higher profit model with the nicer features.
However, Canon did listen, and came out with the 7D a year later, and it had greatly improved autofocus. Its very likely that any new 5D ?? model will also have greatly improved autofocus. If it sells more cameras, they will do it. We likely would have had new bodies last year, except the earthquake and other disasters spoiled the plans.