What's missing is user testing. Many designers are still in denial that they're engineers not artists, they still mock user testing with "users don't know what

What's missing is user testing. Many designers are still in denial that they're engineers not artists, they still mock user testing with "users don't know what they want" etc.. But how do you know if the interface does what it's supposed to do? Does it have bugs? One of the benefits of a platform design language is that users learn the language, they know what the buttons are, how to navigate around without putting too much thought into it. If you deviate from that you really need to be sure the user will benefit from it and it's not just pretty for pretty's sake.