Well, to sum things up:
Primal Ancients are a minor content addition that haven't been asked for and cannot "solve" any major flaws of the loot system. They don't hurt anyone either, so I don't see a reason to complain. They could be better though.
The first iteration was just boring, instilling the notion for some players that they would have to complete a new, much, much longer loot hunt before there was nothing but plvl to gain, again. I can't agree with this notion. I accept that as of now dedicated people are able to have every slot ancient with decent rolls and big augments. But to me, the way to that point is more enjoyable than whatever may come beyond. I can't see anything negative in stretching the time frame, in which loot has a chance to be relevant. One could argue that that's the entire point to Diablo.
The second iteration is even more boring. It's still an addition and now it has virtually no chance of hurting anyone, but as others have said, this is as close to scrapping the idea as it gets. Now there's hardly anything to gain off Primals and a huge portion of the player base is excluded from ever seeing them.
What I would do:
prerequisites: make them interesting, yet not mandatory and be very careful with their obtainability
1. Remove the GR 70 gate, there's no point to that. Maybe lvl 70 and t1 req but no more. By the time I can solo GR70, I'm basically done with a season.
2. Give them a chance to be better than ancients. Maybe give them 5 primary and 3 secondary rolls with RNG rolls at ancient value. That's pure power creep without messing with anything else (like allowing for too much CDR), while retaining the chance to still find something better. Just perfect ancient stats are nice and all, but really boring.
3. Remove them from cube recipes, I dislike the entire concept of farming mats for the cube over actually farming random items. I know we need some ability to target something specific, but vanilla ancients serve that purpose.
4. Adjust their drop chance accordingly, maybe difficulty based (like super low on t1 and noticeably higher on GR70)
5. Give us separate checkboxes in the clan settings to display regular legs, ancients and primals.