I like interesting introspection, but there's nothing to turn me off a book faster then listening to the "good guys" think. I kinda think I associate them with banality, illogic, and a total lack of anything resembling (to me) human emotion...
As people, most of us really, really do suck hard insane. What with all the benefits of presenting a stereotypically good personality, there might be a facade on top of that.
But introspection is incredibly awesome, either with an anti-hero or a villain! If an author can't plausibly do that, can't show their point of view in detail, do they really have a believable villain/anti-hero in the first place? I think, to understand ugly beliefs or actions on the part of others, you have to dissect your own. Sure, we might *think* ourselves forward-minded with our tolerances and all, but..
We're not, obviously. Example: Darfur. Huge humanitarian crisis. People there are living in utterly atrocious conditions. We as people are more interested in the economic benefits of a tight relationship with China. There are major problems like that which would *not* be easily fixed; problems which even the first step toward a solution might provoke an economic downturn, might make things worse in the long haul. It's easier to hold one-day hunger fasts, isn't it?
Can it really be so hard for writers to understand that supporters of slavery and genocide could rationalize their own actions in the same way?