Well, Magic Missile needed a buff very badly. It was by far the worst of the Wizard at-wills, not worth considering at all unless you planned to do cute things with it through feats and items, and really not even then.
Compare Magic Missile to Biting Swarm, one of the "counts as a ranged basic attack" spells that seekers have. Biting Swarm does more damage (assuming at least a longbow) AND imposes a great status effect AND also puts that debuff on every adjacent monster AND that splash effect is enemies only. Until this change, Wizards were screwed so badly in comparison on their "counts as a ranged basic" that I actively avoided playing a Wizard when there was a Warlord in the party.
So MM badly needed a spit-polish. Whether autohit was the solution is a different question, but it's nice that one of the iconic wizard spells is no longer for clueless beginners only, and that Wizard's Fury is now a viable daily. And truly, MM is still not that good. It's certainly not the best wizard at-will, and maybe isn't even the best single-target wizard at-will. Nor is the anything new for wizards to have an at-will that deals automatic damage; remember Cloud of Daggers?
Coming right after the announcement that Burning Hands will be changed to deal partial damage on a miss, it seems that WotC is intent on fixing some of the classic wizard powers that were underpowered in PH1, which I think is terrific. I'm crossing my fingers that Fireball will be de-suckified once Essentials comes out.