Car use is the only valid argument with this whole mess. When I'm charging my phone, I'm either at work, or at home, both locations where I can either just use the speakers, use a bluetooth speaker, or use another device to listen to music (like my work computer). Luckily, I use Spotify (can't get iTunes on my work computers) so that's not a problem, personally.
Okay, so maybe you're out in public. Libraries, Starbucks, etc. If you're visiting these places for an extended period of time that would cause your battery to run out, you likely have another device with you, like a tablet or laptop to accomplish the task that brought you to the public place in the first place. Even if you're not. Even if you're reading a book and listening to music, it'd take a while for you to run out of juice.
The car problem makes sense, because besides the scenarios above, I charge in my car frequently, mostly to top it off from charging at home or work. If you don't have bluetooth, you can't make it happen without an adapter. But back when I had just a tape deck in the car and no aux connection, I needed an adapter. It wasn't the end of the world. I even used those wonky radio transmitters that pumped your music through a radio station. I needed an additional purchase to get the job done because I was using new technology.
I'm not saying this is an easy transition, but I think people are blowing this out of proportion. I can't see anyone who is charging and listening to wired music for a significant portion of their life who, with the purchase of either bluetooth headphones, a bluetooth car adapter, or one of these new Belkin adapters can solve the problem. Or the simplest solution of all. Just don't buy an iPhone 7. Get the 6S and wait for the 8.