[insanejudge]

I've operated by and described the concept of Chesterton's Fence countless times, so that's a great name to learn. It's such a regular thing working with new grads, etc. that they see some "old legacy crap" and their first reaction is to want to tear it out or scrap the whole thing start over.

On some occasions it can be worth the lesson to let them try but it's a good thing to remember that the people who came before us weren't all complete idiots and there is generally a reason why they did what they did.

Sometimes it is gross old code that needs to be replaced, but even then it often still contains a hard fought record of all of the corners and edge cases you need to understand and handle to build anything in that domain.