The margin seems to serve the purpose of holding the utterly important widget that tells you your name, user id and karma.
I find that highly useful because I ocasionally forget my name, I would have *no idea* where to look up my userid if I ever needed it, and my karma? It's changing so quickly between "Excellent" and "Excellent" that I'm having a hard time keeping track of it.
If I might add, a narrower comment section feels more app-grade. Thanks for that, too.
Now if you'll excuse me, I have an app to app. With a margin.