I get what you mean.

Here is the reason why I think Ainz doesn't intend to be the villain the way he is. He wanted to create a utopia where all beings could live in harmony under his rule, so any opposition should be eliminated. If you read the light novels, his rule of E-rantel which will be shown in Season 4, was a peaceful rule. While his undead soldiers occupied the city, everything was bakc to normal and demi humans get to walk in towns without being harmed.