Your inbox example is spot on. Personally I still don’t really get why reminders are part of my email app. If they weren’t trying to include it, they could probably just have a pen (compose) icon, with an alternative solution to quickly direct a message to someone you frequently contact. Still, I think perhaps that’s either a result of my ignorance of the inbox ecosystem, or an identity crisis which plagues so many Google products.
Regarding your response to home buttons, as I mentioned, the iPhone (and almost every other smartphone) has a completely abstract home button, but you seem to be fixating on android. This really is one of those occasions where form trumps function. Having ‘home’ written on the iPhone home button would be obnoxious, and the same logic can extend to the android navigation buttons. I’m really not saying that app designers should be using abstract nav buttons, but just talking about the main android nav buttons which you mentioned in your original article.
The amount of people who would benefit from a home image, or ‘home’ text being applied to every smartphone ‘home’ nav is easily outweighed by the vast majority who really appreciate a beautiful phone. I’m really not sure it’s possible to make everyone happy here, and I don’t see anyone really solving it (no one is rushing to follow Sony’s example!).
I completely agree with you about icons and text for individual app bottom navbars though. It’s almost always better. You make very reasonable criticism of the new Google specs for bottom nav.