In a warped sort of way, I can think it would be useful to have it the other way around. A small developer doesn't have the resources to build and maintain thei

In a warped sort of way, I can think it would be useful to have it the other way around. A small developer doesn't have the resources to build and maintain their own billing system, promotion, etc, so 30% is probably reasonable. A larger developer, however, can, or already has those things, so to being forced to pay 30% is not reasonable. That's before we consider margins rather than takings.