Some of the most successful projects are at the bleeding edge of their implementor's ability. Absolutely as simple as possible out of sheer terror of complexity.
The sequel to this phenomenon is the universal second system effect.
Intellectual discovery can be a powerful motivator in design decisions. Take care when tasking a developer with a mundane or boring task. People have a way of making uninteresting problems interesting!
I have more to say about this, including a crazy idea about the SR71 Blackbird, Lisp and the Apollo Missions all somehow appearing before their time (like from the future ;) )..