As for your interior question of why it hasn't been replicated for other topics, I don't think it's simple enough to replicated. HN isn't monetized traditionally so there isn't a successful business model to replicate unless you include the entire company of Y Combinator.
PG has a great thing going here that is far more valuable to him than money. He isn't aching for food on a daily basis so I doubt he'll ever dream of jeopardizing HN the way it is.
(I note your other point about the standard of the communities on HN -v- Reddit being different, but I have no opinion on the level of discourse on subreddits that would be off-topic on HN.)
In regards the information presented, concise might not have been the best word choice. I speculate that the user base for /r/finance are not the users you would attempt to attract with what I am suggesting. I think if you could bring out the wallstreet gurus, traders, entrepreneurs of all types, economists, etc. as regular users, the site would provide a unique and valuable experience.
No, we have not both agreed that.