[jimbokun]

When the domain is complex, it's even MORE important that the individual components be simple with clean interfaces between them. If everything is too intertwined, you lose the ability to make changes or add new functionality without accidentally breaking something else.

As for Chesterton's Fence, you have the causality backwards. You should not build a fence or gate before you have a need for it. However, when you encounter an existing fence or gate, assume there must have been a very good reason for building it in the first place.