I know that some folks really want there to be some disastrous downside to the Ancients' world or their way of life but, to be frank... between Emet's Selch's illusory Amaurot and the short stories set during that era, nothing has ever been shown to even suggest this is the case. The worst thing anyone can say about them is that, despite being nigh-immortal demigods in their own right, the Ancients were still every bit as human as their successors races.

They weren't creatively sterile—at least two sidequests in Amaurot were dedicated to showing their efforts to create, along with the entirety of two level 80 dungeons (Akadaemia Anyder and Anamnesis Anyder). They weren't infertile, either—they mistake the WoL and friends for children upon our arrival to Amaurot, something that wouldn't make much sense if they didn't know what a child was or couldn't have them. Hell, one of the most popular takes on Elidibus's character is that he was a literal child (he's never called as such, but that scene near the end of 5.3 does suggest the possibility). They weren't a cult of evil conformists who reacted to any display of individuality with murder or brainwashing. And yes, I have seen that take before and it's as ludicrous as it sounds.

Is it really that hard to accept that—whatever nefarious things the Ascians are up to now—the people they once were didn't deserve to be driven to extinction?