Thinking about it, I would propably be more comfortable playing an Al-Qaida member than a US special forces man in Afghanistan. And yeah, I would absolutely find that fascinating, if it was well-researched.
I'm not 100% why, but I think it's because the situation would just be so alien. When things get too relatable, I start losing the "just a game" -feeling.
I don't know why it works that way. Maybe it's kind of an Uncanny Valley
(http://en.wikipedia.org/wiki/Uncanny_Valley), where I'm cool with stuff that doesn't feel too close, and cool with stuff that's really relatable (like in a very good RPG-style game), but uncomfortable with stuff that's somewhere in between.
Meh, I don't know :-P