I don't think there was any indication that Ancients were trying to "eliminate sorrow" in the manner that the people of the Plenty were, especially not when the very creation magic around which their society revolved was the source of many problems and as long it continued to be used they would inevitably invite strife into their lives in ways both big and small.

That might have changed in the aftermath of the Final Days, but we'll never know because they were cut off before they could even start with the debatably unnecessary sacrifices. And no, I don't take the testimony of those two Ancients Venat speaks to as indicative of the whole. There were likely many who just wanted to spare the souls of their loved ones from languishing as part of Zodiark for eternity.