Good system design is boring, obvious, and completely uninteresting. This is why a lot of flashy or trendy techniques end up leading to bad systems—they rope people in because of their cleverness or intellectual content, which often is interesting, but stuff that's new/intriguing/intellectually stimulating is often not what you want in a system.

A good system needs to be as easy to understand and interpret as possible, A good system design is so mind-numbing my simple that a nincompoop can understand it. The only deviations from this policy should stem from other requirements like storage, performance, etc.