The fatal flaw in the movies is that they made Bourne a bad guy. Yes, he is working for the US government so he is a sanctioned killer, but he's still a killer and it's a one trick pony having him realize he is Jason Bourne. The book is so much more intelligent in that regard, and other than the Era having to be updated I don't know why they changed this aspect too. Maybe it would have caused the film to be too long, I don't know. The female lead was a terrible character compared to the books too. Don't know why they had to make her a useless damsel in distress type. The latter films I don't really care about in relation to the books, as due to the first film I knew they couldn't share anything with the books other than title, but the first could have been so much better.