I think you hovered over something significant: yes, most of the "new features" of the new phones are software features … but the line between "what is software and what is hardware" may not be crystal clear to a lot of the population.

Imagine the effect of a TV spot touting a new OS feature on the new iPhone. Do I need the new phone to get that feature? As soon as you've asked the question, you're at the doorstep of "I wasn't thinking about it, but I will need to replace the battery soon ($$) and it's been getting slower …"

You may learn the feature is available in an OS update, but it's inconsequential: you've already rolled the idea of a new phone around and remember how nice it is to start fresh. This one may not get you, but next year's definitely will.

Some confusion around hardware -vs- software is key to draw people in.