Users are able to rate and comment on the entries and, naturally, the game "developers" are going to abuse the ever-living crap out of the service.
Looking at the stuff on the service, it really seems most of the developers are desperate to get on Steam just because. I find it hard for anyone to actually considering paying for most of the games that seems to be quite par on the stuff readily available on the various flash game sites around the internet. I don't see Steam to be a competitor for sites like Kongregate or even Curly's World of Freeware.
For actual indie game developers, this probably is a good thing. The amount of exposure their works can get on Steam is probably a lot more than through other channels. Many of our top games on this site would probably be enormous hits on Steam, if it wasn't for the fact that they're free.

Also, if you thought there couldn't be too many zombie or RPGmaker games...