Post ID's are not that important, but do come into play for some folks.
Link/Post Category ID's are, however, more important and there has also been a suggestion that you can obtain these by a mouseover.
To call this resolved is, in my opinion, a bit of a stretch.
What it really is, is a quick fix to an oversight.
The fact is, the codex offers a multitude of functions that make clear references to the ID numbers for category, link, or post, as one of the options available for that specific function. To remove the ID's from view and require a mouseover is, at best, a quick fix to an otherwise fairly serious oversight.
It doesn't take a lot of code to add an ID column in the Manage Categories page, or Manage Link Categories page.
A resolution to this is not a mouseover, but the ability to toggle ID visibility on or off.