One might also ask why love of warfare is so prevalent in trad, or xenophobia/racism, or any such long-held human attitude that has only become outdated within the last century or so.

A subculture built around interest in the past, or (at least) in long-established and deep-rooted cultural expressions, is not going to reflect values that have only emerged in recent years, since the world has become so much smaller so quickly.

Our current ideas of feminism, universal brotherhood, etc., were unimaginable to our forebearers of just two or three generations ago, so we can hardly expect such enlightened values to be reflected in centuries-old ballads, etc.