In the case of these movies Ludlum's books weren't followed. There was a much deeper storyline and a good deal more antagonists in the books which came out long before the movies.
Example, Bourne actually married Marie who was originally a Canadian Economics's Analyst or something like that instead of the German Gypsy they made her out to be.

Anyways the Bourne movies have their own style. I won't complain because they are just plain hot.

Sometimes in the winds of change we find our true direction.