Obviously, this in-app payment feature was deliberately designed to be irritating and intrusive. Apple understands that, to most paying customers, the word micropayment carries a connotation of being slowly and imperceptibly bled to death by vampires. So perhaps Apple is going to provide an API which turns in-app charges into such an ugly, flow-shattering experience that nobody could possibly miss it -- which will also compel app designers to avoid using this feature unless they really have to.