G. K. Chesterton's parable: imagine you find a fence in the middle of a field with no obvious purpose. The modern reformer says 'I see no use for this; let us clear it away.' The wiser response, Chesterton argues, is 'If you don't see the use of it, I certainly won't let you clear it away. Go away and think. Come back and tell me what it does. Then I might permit you to destroy it.'
The principle: Every long-standing rule, process, or constraint was put there by someone solving a problem you may not currently see. Removing it without first understanding what it solved is how you re-create the problem in a form that takes longer to recognise.