The problem with the old Android menu button was that you never knew whether or not there was a menu, and what would be in the menu. Some apps had navigation, s

The problem with the old Android menu button was that you never knew whether or not there was a menu, and what would be in the menu. Some apps had navigation, some had actions. Some apps had different things on different screens. The usual pattern on Android nowadays is that hamburgers go on the left, actions go on the right. And an on-screen button is much more obvious than a hardware key, or something on the never changing bottom bar.