Pretty vital in my experience. Allows you to have food production away from the town and then put a market in near houses and it collects the food from all the different sources so the villagers get a wide range of food. So it's not limited to whatever is in the houses range.
OK things seem to be going pretty well. I have a self sustaining little village with all the main resources covered. I'm in early autumn of year 3 and I've noticed I only have 1 child. They don't seem to be breeding. Full 5 hearts and stars. Resources look good. What am I missing? Do I need to have idle villagers?
I had two children die in the first year, they decided to go for a very long walk through the forest in the middle of winter and promptly froze, idiots.
Well, made it to year 6 and just had a fire just wipe out almost every building - building by a river and having a well seemed utterly pointless. Everyone then promptly died of starvation!
I tried repairing the essential buildings but nothing seemed to happen
I was getting to the point where I was wondering what to do next... everything was good, everyone was happy, self sustaining, but still no children being born. Bit weird.
Hmm struggling to see the purpose of a market. They seem to just be pointless.