Improve UI Customization - Make the comments toolbar stay open automatically no matter what
In my case, I'm perfectly happy with the way Adobe chose to implement this (I haven't actually tried the upgrade yet - I'm just responding to other comments here). In addition to documents that come to me with comments I need to see, I open plenty of random PDFs that have no comments, and in those cases I wouldn't want the pane to take up space.
But I suppose if Adobe wants to make everyone happy, in a future upgrade they could expand the setting to be a three-item radio selection instead of a checkbox:
Show Comments Pane upon opening document:
● If the document contains comments