The Muslim world is portrayed as a monolith that is consistently scary and negative, and as much as you can be an open-minded person, if the only diet of information you get is scary images of men in beards, that starts to play on you. But you come to find out that the Muslim world is not a monolith.

A true nature is a gloomy monolith, sort of like that old black rotary phone that I had to sing 'Happy Birthday' to Grandpa on. But novelists, damn us, still need true natures - so we can give them to our protagonists. And so readers can vaguely predict how they'll behave when we trap them in 'situations' that they can't IM their way out of.