Upvote count was the "must read" buoy that helped me navigate HN

It would also be possible to bring back the red dot, on high-voted comments. Perhaps the dot can be made bigger as the vote count increases. That would act as a pretty effective must-read signal, I think, without compromising any of the goals of hiding upvote count.

Is there a post that lists the reason for the change?

There's a serious amount of moaning about this subject. I don't think it helps to fill up HN with these topics.