This interview of Matt Thorson is really great:
"I personally don't think the Ouya's audience is big enough to support mobile pricing," he added. "All the arguments towards pricing lower were to cater to people's expectations, and I believe TowerFall is worth $15 if you have people to play with." […]
"On an iPhone, you can charge a dollar and potentially make it back because the audience is gigantic. But there aren't enough Ouyas out there yet."
However, I must confess that I'm a bit surprised that only 2.000 copies have been sold. Even at $15 each.