I don't really see a way that pageviews could significantly increase without a corresponding increase in uniques. The most obvious reason to see an increase in uniques is to have an increase in new users.

Onboarding new users into the HN culture is relatively easy when you're dealing with a steady but slow intake. I'll admit that I can be an ass on reddit and my highest karma posts have mostly been stupid jokes, but I take things serious on HN because HN presents itself as a serious place.

When you get a significant stream of new users, it can be harder to keep them all in line. If you get a bunch of new folks together voting up their own brand of inane crap, it'll start to pollute the front page. A polluted front page sets a bad tone for newer users, because they think that sort of thing is tolerated.

HN has systems in place to stop this of course, like the ability of some users to kill a post outright and the karmic threshold for downvoting, but there will likely come a time when that isn't enough anymore.

I agree that pageviews are generally a good thing, but HN isn't advertising-funded in the traditional sense (by that I only mean that HN does serve as an advertising platform for YC companies to an extent) so having high pageviews probably isn't high on PG's goals list. HN is pretty unique in that respect, and that's a distinct part of its charm.