Also, software is hard to write, and second system syndrome causes loads of loathing and misery even when the goal is to "do it right, aka simple, this time."

That said, sometimes we need to take on the risk and effort of making a second system. I have often thought about the relearning/doomed-to-repeat-history problem, and I wonder if software - especially some open source software - might be uniquely positioned to build a second system due to bug trackers.

The bug trackers in software like Firefox effectively capture a large percentage of a project's history and design decisions. It seems to me that the bug tracker for a projects' predecessor could lay the proper frame for its successor.