I know this thread is two years old, but I wanted to post my thoughts anyways.
I love the idea of tools. DF is a very complex game. The reason I have recently fell in love with it. I agree that making tools at the beginning would be hard to do and add just another task to do per workshop. At a large fortress it could completely halt production if not kept up with. However what if the first automatic task of that workshop is to make a basic tool set out of whatever is available, rock or wood? Later at that workshop or some other one they could make advance tools out of better tools or expand the tool kit they have. This would improve the work and improve the speed its constructed.
Farmers and Fishermen would work without tools but work faster with them. As for people harvesting. How hard is it to pick a veggie or mushroom? You don't need tools. This would still allow all dwarfs to harvest.
As for the idea of sets of tools versus individual tools, I think both should be available. You could make a kit of various needles for your cloth workshop or you can make them one by one. This way could produce a stack of that one needle with a higher value then it would be if it was made as part of a kit. Imagine an artifact hammer that when used no matter if its a novice or master could produce a masterpiece every time? I also love the idea of a farmer beheading a goblin with a hoe than calming going back to work while another dwarf carries away its lifeless body.
Wouldn't it also make dwarfs happier to have tools that makes work easier? Having good tools could produce happy work related thoughts.
As for the tools being replace. If the advance tool sets run out the dwarf grabs a new one if there is one, but if not oh well. If a basic needed tool goes bad they autonomic replace it. That way if you didn't want to you didn't ever have to mess with tools, but reap the rewards if you did. A win win of sorts.
