I think you're being a little hard on academia. It's only thanks to the fairly recent diligent work of American archaeologists that we now know what war mongering, deforesting maniacs the Mayans were, and that they most likely wiped themselves out.

I think the fault may lie with the 'heritage industry' which is what museums represent. They want to attract families with kids to sites with X-rated histories, so they censor out most of the reality.

I've always been intrigued by the way the Pilgrim Fathers are popularly portrayed in America as peaceful, devout folk, cruelly persecuted and hounded out of Europe. That's got to be the heritage industry at work again. Puritans were more like the Taliban; smashing up medieval cathedrals, killing half the population of Ireland and desiring to extend bloody religious war across the whole catholic world.