You're already carrying that device though, it's not an addition to your pocket. In fact, I'd argue the 2nd device is actually a problem.

No, you are. Not everyone reads when they have their phone on them, or otherwise have their phone on them 24/7. When I'm reading, my phone is at least on a table, if not in another room.

Ah, that's fair!

I guess I consider a device like that, for me, to be mostly used when traveling!