Why make pottery?
Because my kids get excited to choose the handmade bowl or cup they drink out of. They have favorite ones for different foods.
I've never seen them get excited to eat off of an Ikea plate or bowl.
If a four year old can tell the difference between a mass produced bowl and one made by some dude in his shed, and somehow appreciate that difference, I think it speaks loads on why a potter might choose to make functional ware.
Speaking for myself, I make functional ware because it makes me feel happy. Every part of the process from wedging to throwing, to making and modifying my kiln, to firing in my driveway, mixing and making glazes, all the way to sanding the feet. They all bring me joy. But the thing that really turns all that joy real, is when someone chooses to eat or drink out of something I made.
So in the case of a functional potter vs. a factory... Where's the joy? It's rather one sided isn't it. A factory worker doesn't meet the people using the things they made, they aren't emotionally attached to the things they make, there isn't happiness in every step of the process, and I feel that it shows.