Does a larger screen and high MP count camera really mean you will use more data? Some of this makes sense.
I have to be honest though. I really believe there is more and more apps or services/processes being written into new phones that somehow use more data in (tinfoil hat) stealth mode. I myself never had the problem till I got my 2013 G2, then noticed more when VoLTE launched and my phone's mobile data would "turn off" but still use larger than incremental data when even on wifi.