I just don't believe it's in Reddit's best financial interest to decrease the level of impact an individual user can have on its site.
I also don't believe moderators, as they're currently designed on Reddit, are capable of discerning signal from noise. The whole driving premise of Reddit is the upvote, and that's an incredibly powerful concept.
Legitimacy is established through adherence to core values, and Reddit's core values have always centered around what's popular, not what's "good" or "right", as judged by a few randomly selected people.
Reddit is the upvote, not the moderator, isn't it?
Edit: Sorry, this is a little rambling, but I'm torn between spending 20 minutes fleshing out this comment, and being a productive employee (aren't we all?).
The overall gist of what I'm saying is the idea of a more "curated" Reddit, a la HN, would be bad for the website, the Internet, and the company primarily because of the lack of any kind of vetting of those who would curate the various reddits. I think there's a place on the Internet for a very profitable website that doesn't have any particular "quality control" beyond what the users like and don't like (janitorial tasks, e.g. spam filtering and illegal content pruning aside).