From the post:
Good app ideas are a dime a dozen. Your great idea isn’t guaranteed to make any money in the app store. Why should a developer develop your whole app for just a percentage of the money you are going to make? Just because you have a good idea? Most developers have good ideas too, and if they are going to risk not making anything for their hard work, they might as well balance that by doing their own work and making 100% of the profits.
