@peter I think a bit of it is people discovering he wasn't the all-evil-all-the-time cartoon villain they'd been told about. A fellow who teaches a terrorism class says he sees surprise in his students when they learn that. And in our binary thinking, finding out someone bad was right about something can lead to some messed-up conclusions. Getting people to the level of "he had some legitimate grievances, some bad ones, and took very bad actions and is overall bad" is hard.