Also, our idea of a sympathetic character changes a lot over time, too. An authentic historical "hero" from many eras would have thought nothing of owning slaves (or something close to it), would be content to shun a lower-status woman who had been raped because she brought it on herself somehow, would have no problem with preteen girls being forced into prostitution, and would have taken an extremely lax view of fidelity in marriage (at least for the male half of the couple). But try to put any of those qualities into a book for modern readers and everyone would hate the character. Similarly, it would be hard to sympathize with a female character who truly believed she was not capable of making decisions, exerting her influence on anyone except servants/slaves, or doing anything except sewing and housework.
I know I'd much rather read about the historical anomalies.