I imagine "Seduce Me" didn't help this cause, either (despite the legitimacy of that game).
The price is simultaneously quite a bit and not very much. If you are already developing an indie game for the public, this is a small hurdle that you can probably overcome. But knowing that you will have to pay $100 to put it up may deter your neighborhood geek from deciding to make a cool game for Steam. So paradoxically, the price is too high and too low.
But here's an idea: make it a requirement to submit a functional demo of the game. Legitimate developers would be able to produce this with ease, whereas pranksters would have to submit a fake demo, which the community would frown upon and downvote. Seems fair to me, but Greenlight is still foreign to me.