Loki’s villainy has also gained some complexity recently when Marvel changed his official bio to confirm that during 2012’s Avengers he was being influenced by the Mind Stone in the Scepter.
He had the negative impulses already, but he may not have acted on them to such a degree without that corruption.
This doesn’t necessarily take away from the lives lost because of Loki’s actions, but as Stannis Baratheon once said, “A good act does not wash out the bad, nor a bad act the good.”