Usually people who write these things are not genius' they are people who are bored and have time on their hands. It doesn't take that much skill to write these types of worms/virus (We wrote simple boot sector virus' in college), all you need to know is some simple programming skills. You just need the time and nothing better to do so you just keep trying simple variations in your script until something breaks. Most of these kind of exploits are released this time of year as kids start to college, they pay their tuition, room and board, books, etc then have no $ left over for beer so they sit in their dorms bored. Its also why they don't consider the big picture effect of their actions, they are not genius' nor are they quite mature enough to fully understand the effects.