I think amateurbuilt hit upon a distinction that helps this thread a bunch.
When I think "experimental" I think of Jim Bede or Burt Rutan and the like, who produce real innovation in small scale. This innovation cannot be squelched by regulation without choking off progress. I would not look to Cessna or Piper to innovate light plane engineering, and shudder to think what would happen if a board of experts made the real innovators dance the right dance prior to flight testing.
The fact the we also call kit built more or less standard aircraft as "experimental" is perhaps where Ghengis and I do agree. Here, the well intentioned amateur can get in lots of trouble, while not adding to our collective knowledge in any real way (except create more Darwin chuckles).