Smartphones are devices made for content consumption with a phone added on top.
Not consuming content would be misusing it. Like buying an expensive TV to watch the news once a day.
Why waste money on things you won't utilize most of the time?
First off, I think you're misinterpreting what I mean with 'misuse'. I meant it in the context of 'health', and I don't really care what the intended purpose was. The television, for example, is a great invention and I love watching shows and movies in the comfort of my home. You could say the 'use' of a tv is that you watch as much as possible so advertisers can make money. I think we can still agree that watching tv all day is 'misuse' when it comes to your mental or physical health.
Second, 'content consumption' is a bit vague. I'd say a smartphone is worth having because so many people use whatsapp instead of sms, because it has google maps, because I can check my trello board occasionally, because I can check the weather, and very frequently to find out how to get from A to B using public transport. None of that requires me to be constantly 'consuming', but it's still very useful.
In fact, For a full two years I had a smartphone (Nexus) with no data plan, and it was still worth having. It functioned as my calendar, notepad, dictation device, and even maps (although it is less useful offline).
Not consuming content would be misusing it. Like buying an expensive TV to watch the news once a day. Why waste money on things you won't utilize most of the time?