Original diadem was designed as an hunting grounds of sort to give an alternative way of obtaining gear to tomestones and raids and honestly I don't feel like I coul, and can, criticise it for beign a farming grounds because of this, however it had several crippling flaws imho which from my knowledge noone actually spoke about:
Ilvl entry barrier set too high; 179 ilvl was obtainable only with tome gear + a mix of upgraded tome gear and gordias normal gear(or esoterics gear)which in turn made only the highest gear in diadem useful for anyone while making the more common gear only brass spoil fodder completely invalidating the orginal concept
Then there was the problem of the tagging and the general strength of enemies, only with a full party you could actually do something there in a reasonable amount of time, making easy and normal diadem kinda useless once hard was unlocked.
As the last crippling flaw I think the drop of items were on the low side, since I believe that randomized gear should drop very often to counterbalance their randomness or make their randomness less wide if you don't want them to drop often

Personally I was surprised that they actually fixed the first 2 problems because there was no1 that was vocal about those points and so I think that while ppl call the devs lazy for making diadem a fate zone they have their focus on the things, granted they should avoid making fates any less popular than ever with other things like yokai or atmas( and at the same time I would like for ppl to just drop this fight since fates are here to stay).
I too Hope they won't sour the diadem expirience and instead use it to make it better