Artistic license is what I believe they call it; in the same way that Tom Clancy's Rainbow Six version of Hereford bears absolutely no relation to the reality.

With Bourne, I would imagine the producers were drawn by the man in jeopardy aspect of the plot; the premise of just about every Ludlum book, as I recall. The plot itself, however, is well out of date, hence the divergence. If you would prefer a more book accurate version, check out the Richard Chamberlain mini series. Given that it had the budgetary constraints of a TV film it was still, nonetheless, quite enjoyable.

As for a fourth film I, like Bob, have mixed feelings. I thoroughly enjoyed the first three (unusually, they got better as they progressed) and welcome the prospect of a further episode. I’m concerned though about the plot (what would draw Bourne out of retirement?) and how could they possibly better what’s already been done? I’m fearful of the result being too outlandish.