I once flew a Stampe from the front cockpit. The rear cockpit had the usual array of VFR instrumentation, but in the front there was a throttle, mixture, stick, and rudders.
All the instruments were cut out of a magazine and pasted onto the panel!
The chap in the back kept an eye on Ts & Ps and fuel, and I just flew the aeroplane!
It's not that we have too many instruments in simple aeroplanes, it's that we have too few pilots trained not to need them.