Two huge reasons keeping developers on the iPhone -
(1) Ease of development - cocoa + objc isn't very hard, and often is quite fun. Its roots in smalltalk help in the appeal to ruby/rails people, and, let's face it, cocoa apps are just plain sexy
(2) Non-Apple / Android handsets have a terrible distribution system. Carriers are in the stone age and have no intention of budging one bit. I've gotten back evaluation reports from carriers with complaints like how their bottom-end, 25-character wide phone screen couldn't read text, thus they wouldn't ship on any phone. It's attitudes like this that scare the crap out of developers.
The only people I've met who have either of those devices are "business people" for lack of a better word. A market very different from the iPhone crowd - the hype certainly isn't about bussiness applications. Maybe the demographic is different elsewhere.
(1) Ease of development - cocoa + objc isn't very hard, and often is quite fun. Its roots in smalltalk help in the appeal to ruby/rails people, and, let's face it, cocoa apps are just plain sexy
(2) Non-Apple / Android handsets have a terrible distribution system. Carriers are in the stone age and have no intention of budging one bit. I've gotten back evaluation reports from carriers with complaints like how their bottom-end, 25-character wide phone screen couldn't read text, thus they wouldn't ship on any phone. It's attitudes like this that scare the crap out of developers.