who thinks it's wrong for film to revise history?

I don't think it does.

Movies are made for entertainment,not to teach history,and factual inaccuracies in historical movies are quickly pointed out - for example there are whole websites devoted to the such inaccuracies in 'Braveheart' and 'The Patriot' and if the ordinary person wants to know more after watching a historical movie,they can read up on it themselves - it's really not that hard.

In 'Glory' Jupiter is whipped for leaving the army camp without permission - a military crime that a white soldier would have got the same punishment for,and that was standard throughout European armies as well at the time (for example,flogging in the British army wasn't abolished until 1868).So,I don't see how that particular scene drove any wedges between any cultures,and anyway there were doubtless numerous instances during the Civil War of soldiers being flogged as a punishment,so the scene is largely historically accurate in context.

Don't watch a Hollywood movie expecting a history lesson - I never do,because I won't get one,and know so in advance.

Films have always altered history to make a better movie.

Sometimes they take a group of people and pour them into one, like 13 Days.

Sometimes then alter time lines for better scenes, like Young Mr. Lincoln.

If you are trying to learn history, movies are the last place you want to go.

If you want to be entertained, well, there you are.