Ouya has a much lower barrier to entry than Steam, which is none. Anyone can publish a game to the Ouya market (at least that's my understanding) but for an indie developer, getting a game on steam can be quite difficult. See the recently launched Greenlight website and how many games are on that, trying to get published on Steam[0]. I think the ease of publishing will attract a lot of developers, in the same way that iOS/Android grabbed smaller developers that couldn't get on the old consoles.

[0] http://steamcommunity.com/sharedfiles/browse/?browsefilter=m...