IMO, the higher barrier to entry is a benefit to this site. Features that would lower friction increase content dilution. From what I understand, this site is not trying to become Reddit.
And an API, practically by definition, is not a benefit to membership or a draw for whatever HN considers a typical user, much less the sort of "normie" non-technical user HN wants to keep away. The quality of comments is not maintained to a high standard by the API being more difficult to query than it could be, nor would it be diluted by the API being easier to use.
And as far as Reddit goes, a lot of content gets posted here from Reddit, and a lot of the userbase here are also Reddit users, making the cultural contempt HN has for Reddit more than a bit hypocritical.
A lot of people here, pg included, seem to assume that the "low tech" nature of the featureset here is keeping some flood of unwanted users away but I submit that the title of the site being "Hacker News", it being on a subdomain and the lack of evangelism on mainstream social media do a far better job of gatekeeping than purposely adding "friction" to frustrate people.
HN is for the intellectually curious. Many of the posts here are technical but there have always been plenty of non-technical discussions as well.
A lot of people here seem to believe the site is supposed to be for technical users and technical content onlym even though that never was the case. The negative impressions people seem to have about "turning into Reddit" or non-technical content diminishing the sites' quality feed into that stereotype, as does the belief that adding "features that reduce friction" would somehow dilute content.
But... the guidelines do use the qualifier "anything that good hackers would find interesting" for determining what's on topic, which does lead people to fill in the blanks for what a "good hacker" should find interesting.