Schadenfreude - people want to see the pictures - it is human nature. Think of it as reality television gone horribly wrong.
Ever wonder why an accident scene attracts people and will stop traffic even on the other side of the freeway?
I had a friend who wanted to carry a manikin head in the car so he could toss it out when going by accident scenes so that people would have something to look at.
It makes more sense now why microsoft pulled their support for the gay rights bill in Washington state -- they needed to throw a bone to the conservatives so they could get what they wanted in this arena.