I think it’s also in large part due to the human tendency to simplify reality. Reality is often complex, but we prefer to thing in categories, like black and white. And so you often see people thinking in or blindly accepting false binaries. Side A bad, so side B bad.
Agreed.
Nuance is difficult, and arguably more to the point, it's sort of vague and insubstantial, not least because an awful lot of it necessariky boils down to "I don't know." People generally prefer something more solid to which to cling, so tend toward absolutes and unjustified certainties. And the most attractive ones are binaristic, because then you don't even have to provide support for your claimed position - all you have to do is find fault with the (generally falsely dichotomous) alternative.