Up until now, basically all voidsent we've seen were evil so the angle that there are some who are still coherent enough to resent the state of their world and desiring salvation rather then endlessly trying to escape into the Source and shards simply to prey on their inhabitants or just generally make nuisances of themselves is new.

The Ascians have always had shades of there being more depth to their motives since ARR, but voidsent have not really had that sort of nuance applied to them at any point.