"They were bringing back the memories of how African-Americans picked cotton, and it wasn't a good memory."

And that's why it's a memory to preserve and hold on to. It's a song about black workers refusing to be ground down by slave drivers, and their successors after the formal end of slavery.

If they were singing it in a way that seemed to airbrush the oppression out of it, and suggest it was all happy folk singing their hearts out in a time that was really pretty good, it'd be quite right to object to that - and for all you can tell from what I've seen that might be what it was happening.

hat quote there rather suggests that that might have been the case: "It's like a Southern type of folk song. I remember it being perky. It was more of a song that people just sang for fun".

Treating it as "perky" and "fun" seems to show a lack of respect and sensitivity, where respect and sensitivity is important - becuiasde it is a song that should be "...bringing back the memories of how African-Americans picked cotton", and those are not memories that no American, black or white, should see as "happy".