> You could also argue that for someone using Google products, it makes sense that they look and behave roughly the same no matter which platform you're on.

That is true if you expect Users to change between devices. But most of the users I observe have only limited amount of devices and typically stay in one camp (i.e. iPhone+iPad) and those care about not having to relearn each UI for each app.

True Google tries to push their design as their identity, but that's Google's interest, not the user's.