Chesterton's Fence doesn't tell us _not to change things_ or even prescribe some level of _incrementalism_ it just asks us to make a good-faith effort to _know_ why the thing we want to change is the way it is before we change it.
To follow the metaphor, maybe the reason the fence is there is because the county water supply is behind the fence and they put it there to stop cows and livestock from fouling the water.
To follow the metaphor, maybe the reason the fence is there is because the county water supply is behind the fence and they put it there to stop cows and livestock from fouling the water.