What if you can't afford real, certified avionics systems? After all, we are allowing experimental/homebuilt aircraft into the discussion, aren't we?
Light airplanes don't necessarily require powered controls, so mechanical can still be reliable, even if it is complex compared to a similar un-powered controls.
When you rely on electronics to make the aircraft handle the way you want, you are compromising the design in terms of the level of redundancy. Of course, this may be fine depending on the application. But there is still plenty of reason to research new designs, as they may suit some applications better.