[lostalex]

Because their motives weren't exactly mysterious. It's not like it came out of the blue. remember 9/11 was the SECOND attack on the WTC. The first one in 1993 by the same group.

Everyone already understands exactly why they did it and how they did it. They were just pawns in a much larger organization. So they as individuals are not really very interesting.

It's like asking why there isn't more interest in every husband that kills his wife. We already know why they do it, we understand that some men are just controlling jealous abusive assholes. It's really not interesting at all. The victims are far more interesting and the victims rightfully get more attention.