Just curious: would you consider Saving Private Ryan as being 3D heroes, 2D villains?
But idk I feel that's a silly complaint when the movie is being told solely through the eyes of one side.
In 13 Hours do you get a nuanced look at the motives of the attackers? No. Did it make the Libyan people look bad? No. So yeah I would say that the villains weren't fully realized characters at all.
It's like 90% of other war movies from Saving Private Ryan, Letters to Iwo Jima (from what I remember), Platoon (although Platoon did show American soldiers being extremely f***ed up), Lone Survivor, etc. They're being told through one side's eyes, so you're not seeing what makes the other side tick. It's mostly just showing America doing there thing
This isn't like Pearl Harbor that had those weird Japan, wearing all black, planning scenes. This is showing a group of American former soldiers and soldiers trying to protect other Americans from getting killed. Simple as that.