In my opinion, Engerraund Serac shouldn't be looked at as a villain, or even as a bad guy, but rather as a tragic hero who was simply outmatched.
We see how his home (Paris) was nuked to oblivion in that scene where he and his brother (Jean-Mi) interacted with the guys in the hazmat suits. He knows that the only thing that could lead to humanity's downfall would be humanity itself. He merely wants a world of order instead of one of chaos - because he knows that if there was chaos, humanity would be ifighting itself again.
The Hosts obviously think that Serac is in the wrong. Their world is isolated, insulated, and the absolute worst that they have experienced is people coming in to enact sadistic acts on them. Not trying to condone it or anything, but it pales in comparison to having an entire city - one with so much historical and cultural significance as Paris - destroyed completely. They never really got around to seeing Serac's point of view, mainly because they never would understand.
He doesn't do his malicious acts just because, or for money, or for "power" (like many other villains across pop culture). He does it because in his mind, he knows that a world with chaos is a world where people die. He does it not for malicious intent - but rather a noble one, that of saving the world - and I think that these should all be considered.