The OP said "want to do," though, which is pretty subjective, right? I don't actually care about not being able to use a different browser engine, but I do care about not being able to set a third-party mail client as my default. There are things that I want to do on my iPad that I can't, but not all of them have to do with Apple platform policy -- UIKit's lackluster text editing components are undeniably contributing to the relative suck of Scrivener and Slugline on iOS compared to their Mac counterparts, for instance. (Although one might argue developers might be motivated to work more on homegrown components if the App Store was structured differently; personally, I think Apple's 30% cut is not the worst problem.)
>> I don't actually care about not being able to use a different browser engine, but I do care about not being able to set a third-party mail client as my default.
Has anyone actually noticed that if you use Gmail on iPhone and you’ve got Chrome installed it will use Chrome by default?