You should be able to specify which hearthling does what task out of digging, building, supplying, and job. Instead of just each hearthling either being allowed or disallowed to do something, there should be different levels. For example, there could be four priority levels on tasks: None (wont do the task at all), low (will do if all other tasks are done), medium (will do if there are no high priority tasks), and high (will do these first unless town is on alert mode). I just think it would be useful because I always force my hearthlings to dig by disabling all their other tasks, and then I forget, causing them to stand around idle once all the digging is done.
unfortunatelly that would take pretymuch an entire rework of the AI as is, so i dont see this happening any time soon (since the only people working on this game now are modders)