Banning Mein Kampf was not on the bad side of history. It's rarely black and white.
Also you have to have a very cartoonish view of people think we're like the Hulk and turn green the moment you come across a copy of Mein Kampf, denazification was a broad cultural project, not a binary thing about one text.
The primary struggle with that book is actually reading it because it's simply horrid. If you wanted to prevent Germans from turning to nationalism you'd probably have taken Thomas Mann's political writings off the shelves.