As someone who has occasionally been known to "fly" aircraft in FS2002 but has never flown in the cockpit of a real aircraft I felt tempted to put "finger to keyboard".
The first Flight Simulator I ever played was on the ZX81 - at that time it seemed incredibly realistic, but looking back now it wasn't!
Now, 20 years on we have something that is much more realistic but only really from a visual/ procedural point of view. Yes FS2002 will teach you the basics of flying an aircraft, you can learn how to fly instrument approaches, fly VFR even have your "first and second officers" call realistic checklists on pretty much any kind of aircraft you want. It is also a much cheaper option for those of us that cannot afford to fly for real.
However even though it is realistic and for me provides hours of enjoyment, does anyone here really think that someone could fly a full sized airliner based on knowledge gained from just flying FS2002?
Sure, it may have contributed to the "training" of the September 11th terrorists, but then I expect they read books and training manuals too and as was proved shortly afterwards had actual flight training in real aircraft and probably full sized simulators.
Getting back to the original question - Are home computer flight sims too real? No they are not. If anything, they are not realistic enough. You cannot ban everything, just because of what somebody fanatical might do.