There's a ton of legit reasons to not have a smartphone.
Most of the "arty" types you see probably just can't afford one. As someone who over the years has lost their phone a couple times and dropped it many more times, no way am I going to shell out hundreds of dollars for a new one every time that happens.
I also don't own a smartphone because I already spend enough time at my computer, and doing all the same things on a tiny screen with no mouse/keyboard/etc. would feel like a massively downgraded experience.
For me, the only appealing features of a smart phone are tethering and GPS. I'm fine without them though. I moved to a new city ~6 months ago, and I already know my way around much better than most (especially useful because most of the city is not well documented on Google Maps / OpenStreetMap). Probably would not be the case if I had GPS everywhere.