This.
I'm currently playing a human wizard. He has one spell that's repeatedly won battles. Storm Pillar. Urban environments (cramped battlefields) + storm pillar = win. His other two At Wills are Freezing Burst and Thunderwave (he also used to have Chilling Cloud instead of Freezing Burst - but the fighter has cold resistance). Would Magic Missile be better single target DPR than anything else he has? Yes. Has he ever wanted to cast it? Only when the bad guys are too far away. Beating up on that last one monster is about the only time he's wanted it.
Meanwhile he's thrown people off cliffs with Freezing Burst, blocked columns of reinforcements with storm pillar, and thrown someone the far side of a door and slammed it hastily with Thunderwave. By the time Magic Missile is worthwhile in the average fight, they are already in a mopping up exercise. It's the early rounds that matter. (And if I were calculating just on DPR, I'd be playing a sorceror). Hmm... the one time I'd probably want Magic Missile would be against a Solo. And there I'd be far better with a debuff (Chilling Cloud if our tanks could hold it still) because a -2 to hit would be giving 5 monster-equivalents a -2 to hit. And that is easily worth about the average five points of damage the Magic Missile would do. The only reason my wizard would even consider MM is if he picked up a Masters Wand of Magic Missile (and frankly he'd rather have a Masters Wand of Thunderwave).
Oh, and KarinsDad, a Wis of 13 is required for the Enlarge Spell feat. Which rocks so hard that it's well worth giving up that 20.
My friend in our campaign plays an enchanter and I find that although is damage is pretty crappy his controlling is exemplary. That being said MM is really a niche spell and there are quite a few situations in which it is outshined by other at-wills. I'd have a hard time justifying it as a choice for an at-will personally with my playstyle.