I'm going to guess that political writing hasn't totally worked out either. I think it was plain from this piece that he thought writing was important, but it wasn't something that he was passionate about. If you're going to make a career of writing, you have to be unable to NOT write.
Anyway, when Aaron wrote that, he was 20, and now he's 25. At this point in his life he should be allowed to try and abandon different philosophies without censure. Actually, maybe we all should be. ;)
On the overall point, I think picking what you do based on "importance" is a fallacy. We don't often see it in comp-sci, but this happens all the time to graduates of law school or med school who have tremendous discipline but little self-knowledge. Almost a decade later they find they hate practicing law or that sick people just make them depressed.
Importance is good. But you also have to pick the thing you're suited for and that gives you some pleasure. Otherwise you will get burned out. I can't help feeling that this also had something to do with Aaron burning out on programming; instead of seeking things that he just likes, he's been drawn into doing "important" things, and judging his own work that way. I wonder if, given his history, it is hard to escape the feeling that he has to work at some world-class scale or do mega-important things. It must be hard to just try something with beginner's mind again.