When I did my initial flying training I used FS200 to great effect to help me with my scan and to help with learning to do holds and other basic intrument procedures.
FS isn't perfect by any means and neither are any of the add on packages, however they are much better than just looking at dry text and theory on a page. They give you a good impression of how the systems work in conjuction with each otherand give you good familarity with the cockpit.
We are not looking at if a flight simmer could go out jump in a B737 and go and fly the line. We are looking at if they would assist someone with basic flying skills ie a PPL to direct the aircraft in a straight line until they got to the visual segment of a terrorist attack. VOR navigation isnt brain surgery, and a long visual line up to a building could be easily practiced in FS. These guys dont need to get the aircraft into the air or get it down in one piece in bad weather, just fly in a straight line using an auto pilot and disconnect or use the heading bug in the final stages. FS can easily teach you these skills.
Who am I ? FS fan before I learnt to fly for real, and currently an B737 line pilot in the UK with ATPL.
(Still have fun with FS from time to time)