Well, to be fair, we don't think it's shit, we just don't think there are enough potential customers for the investment. It's not just "build to another store" - my servers have to have yet another push notification service route, I need to coordinate another App Store release schedule, I have to implement another IAP framework, implement another signing path, and buy and test another set of devices.
That's money, baby. Lots of it. And unlike Mr. Bezos, I don't have thousands - let alone millions - of dollars to burn.
It's the same reason we don't build to Windows app store or Blackberry app store without incentives from Microsoft or Blackberry to help get us there.