Why doesn't Hacker News improve its UI?

HN is made for a specific audience, the minimal UI supports the idea of dense information without distraction.

It’s fine. Why fixing something that isn’t broken?

Making that observation is an rite of passage on HN.

What do you believe needs improving and why?

The community can make whatever UI it wants, using the API:

https://github.com/HackerNews/API

I wrote one for myself:

https://hn.unlurker.com

Or there are various ways to restyle the main site with a browser script.

The only requirement from me is to add favourite button to the main page.

How would you suggest to improve it? In my opinion, for its purpose, UI - and UX - of Hacker News are pretty much close to perfect.

I'd like to see the gray body text become a little blacker, but that's about it.