Greenlight:

I am fine with the $100 because I assume it goes with their purpose of the Greenlight. It isn't a way for any game to get on Steam, but rather a way to let a few games get on Steam without them doing most of the leg work.

The game makers put it on and they have to get the votes to put themselves on Steam.

I suspect they only want a few games per month, if that to get on Steam through this method. Look at the game's rating %, I have seen a few 15% but nothing really higher (granted I looked a lot yesterday, not today) but if on the first few days of this and the highest at 15%? Its a long process with a lot of people needing to push vote.

I really don't think it was designed for games that are side projects, but rather serious games that using this as their first push into a major publishing company, why the limited so much. Also the money does go to a good cause. I have only taken one Business and Law class but would that count as a charity contribution for the game company or Valve? One is getting a tax break, could be used by Valve to help their bottom line :P