Maybe because it's the main book chosen by the cults that rule over the Americas today? And most commenters here are American.
If it were a Venn Diagram, the circle of the people subject to the other 'big' religious books would have very little intersection with the set of the people who frequent this forum. It follows then that they would get far less criticism, since there's so much less exposure.
A bit off topic, but I find it interesting that the Christian Bible is always the example of a "bad" book, when there are other, very popular, religions whose books literally tell them that non-adherents are worthy only of a grisly death.