As a fan of the historic film I think the key problems are the desire not to offend some groups while trying to create a commercially viable film. Both of which can send any attempt at a honest depiction of a period or event all but impossible. Take the comedy 'Sweet Liberty' as a perfect example of where a desire to make a historically viable film goes to the wall.

Or 'The Last Samurai' instead of taking the real and totally amazing story of the rebellions at the time of the Imperial restoration we end up with 'Dances with Wolves' with swords and ninja's. Entertaining but if taken as historic fact, which people often take these films as, we get a total foggy mess.