pg puts his time and effort into managing the community, rather than the page controls.
He's repeatedly, periodically made comments on efforts to improve moderation, filtering, ranking, etc. And those efforts are evident in their effect upon content.
"Stagnant" is not an accurate description.
Finally, HN is a tool -- a tool for communication. In that respect, it works pretty well, and is actually somewhat UNIX-y, I'd argue. (E.g. leaving notifications to external add-ons, private communication to email et al., etc. HN focuses on its core purpose of posts, comments, and ranking (public discussion).)
P.S. This is, obviously, just my observation and opinion, FWIW.
P.P.S. Sorry -- rereading the parent comment, I think we are more like-minded than I first thought.
One might say pg has focused on the message, rather than the presentation. Which has worked rather well. Although I think I and some others are also just fine with the presentation -- readability over eye candy, and with the effort put into other aspects of the site.
And... as some have observed, sometimes it is suspected or outright apparent that supposed "limitations" are actually a feature. For example, limiting disruptive, low S/N back-and-forth commenting.
I guess I've written all this in part for the benefit (if any) of some newer members who happen to read this. Experiencing HN over a longer period of time, I've found perhaps (presumptively) somewhat deeper insight into pg's and the moderators' approach and management.