[h2odragon]

To gain a better understanding of why the one that's there is designed as it is. Sometimes there's legacy crap in the previous design thats no longer needed, or you have better materials, and can make the new one more elegant and functional. Sometimes it just gives you the opportunity to see all the failure modes that weren't obvious until you stuck your paper wheel in the place where a steel one had been.

[RicoElectrico]

This is one of the most common mistakes in software development: not appreciating that the true value of code is the knowledge embodied in it over time.