foole:
I see what you're getting at: closed platforms are harder to write code for (or against). But harder does not mean impossible. And I don't think Apple's control of what gets put in the store means they necessarily do much testing on the apps. I certainly don't expect the apps I install on my iphone to have undergone a rigorous testing process by Apple.
Closed platforms can actually be easier to write code for.
1. You don't have to worry about coming up with an innovative UI, because the UI is strictly enforced and automatic.
2. You don't have to worry about different hardware or drivers. Even though OS's like Windows are supposed to hide HW/driver details from you, they can still often require application workarounds.
As long as the API is developer-friendly (i.e. the PS3 API doesn't fit into this category), then I would say a closed platform is much easier to write for.