In this case I hope you have sympathy when I state that I dislike when Apple charges 30% on transactions (but also apps), because this cost is also passed to the consumer: me.
And I 100% guarantee that the piece of this 30% pie is way bigger than the effort it would require them to divert their development like you're suggesting.
EDIT: Oh, and I also bet their lawyer bill for fighting this is bigger than that too. :)