I agree that information density can be lacking with some of the redesigns... but I want to point out that if you're able to read HN on a mobile screen it is because you are blessed with youth and/or good vision.
A lot of us can't make out the text when it is so small, so a ton of pinch-zooming is necessary, which is a rough user experience.
(That being said, at least pinch-zooming is an option... nothing bothers me more than when a site actively disabled zooming on mobile with the god-forsaken "user-scalable=no" meta viewport attribute!)