Apple and Google not only created the device and funded the R & D for the features, but also created the APIs, the tools, the infrastructure, and attracted the (hundreds of millions of) users. The 30% cut they ask of developers is more than reasonable. Want to bypass that cut? Build a web app and make it play well on mobile. If you want to run it on Android and iOS devices, then I don't really see how anyone can say…
Do you believe this with regards to laptops? Laptops masquerading as tablets? Tablets? If not, why? And if it was the case with laptops, i.e. near 100% of users are on only two OS's both (and especially one) of which effectively force native apps through their channel for discovery, would you change your stance or accept that as a reasonable development/computing model for native development?