Certain things are definitional to D&D, and the six ability scores are high on that list. Players are deeply attached to them. 4E was an object lesson in the dangers of changing such things, and even 4E didn't venture to touch the Sacred Six.
You can argue till you're blue in the face, marshaling all the logic and design sense in the world, that the game would work better with only four stats. You may be right! I believe the game would work better with none at all. But Wizards is never going to change the lineup. Hell, I wouldn't if I were in charge of D&D--the benefits do not justify the risk.
I do think it might be possible to push D&D back toward the 2E model. In 2E, the secondary bonuses from ability scores (attack and damage bonuses, hit point bonuses, etc.) were much smaller than in 3E and later. However, when you used a nonweapon proficiency (the 2E equivalent of a skill check), you added the whole score to the d20 roll*, so there was a really noticeable difference.
I'd like to see 6E move in that direction. It probably won't, though.
*Well, sort of. You rolled 1d20 and tried to roll less than or equal to your ability score. However, nobody wants to go back to that kind of system; the "higher always better" equivalent is d20 + ability score vs DC 21.