Personally speaking, I think it would be best for the game, if all the hard version dungeons would just replace the normal ones, or kind of get merged together and replace them with actually new different unique dungeos.

It has from begin on never been fair, why only some specific dungeons received hard versions.

Copying old content and making it only harder is just a sign of lazyness n missing creativity on the dev side. However, undoing that now is impossible, the damage to the game is done and its unrepairable by now, without causing lots of new problems, so deciding on stopping doing them was probably the best decision, even if it looks in the end like a total stupid fail design, that only like a handful of dungeons from xx have also hard versions, while all others don't have that. It will give you as player the impression, the game is just incomplete and unfinished