Yesterday I noticed that my iPhone 6S has stereo speakers too. The same way de iPhone 7 stereo speakers are working. (Bottom speaker + earspeaker on the front). What I did: Open spotify and play a radio. Then go to a whatsapp chat and press the foto icon. The camera will pop up and your music will come from the earspeaker. So basically Apple disabled this feature with software and the iPhone 7 isn't so upgraded after all.