Our teenage son carries a flip phone. Always has, always will, until he can pay for something else.
Turns out it still had a rudimentary browser. And because the phone was only capable of 3G, his basic line had unlimited data. He spent a ridiculous number of hours watching YouTube on that tiny 1.5" screen.
The main reason is how worried we are about the impact unfettered, always on, modern Internet/technology will have on the developing brains of teenagers, and beyond.
Besides that, I have very few apps installed on my phone. I basically use it as a mobile web browser from time to time.
That said, I have to admin that the "features" I'm missing are a camera and a map.
I'm told by people who do have some actual talent that a small fraction of the pics I take are good.
For this picture, I was actually riding my bicycle, and snapped two dozen shots over 30 seconds.
I used it for telling time, taking photos of maps and other useful notes, etc. Super useful.