The main idea behind the light sport rule was to impose regulation on two-seat ultralights that were previously flying under Part 103. Go read the final rule and the accompanying text from the Federal Register on July 27, 2004. Straight from the horse’s… err… mouth: “ As stated in the proposal, the FAA intended to limit the definition of lightsport aircraft to primarily address the population of ultralight-like aircraft that are being operated under exemptions to part 103 to conduct flight training.”
The FAA honestly expected the majority of LSAs to be slow, open-frame, no-electrical, tube-and-fabric designs that were basically direct descendants of “fat ultralights”. Even if we ignore that the bar for that was set so high as to make such fat-ultralight aircraft uneconomical to certify or produce, everyone else looked at the rules, said “hey, cool, I can fly without a medical!” and the manufacturers proceeded to design aircraft right up to the limits (perhaps with a wink and a nudge). Because that’s what normal people do.
If you want more designs and lower cost, you deregulate—or just go E-AB/E-LSA, which is where I truly believe the future is for almost all new light aircraft, except for commercial applications and high-end personal purchases (new Cirri, light jets, etc). Attempting to “streamline” Parts 21 and 43 will just wind up being as ineffective as the Part 23 rewrite has been.
In the short term, the FAA needs to do what its own working group suggested 7 years ago—implement the “Primary Non-Commercial” category, except ditching the nonsense idea that anyone will want to convert their airplane back to standard category. Why would they? An airplane the owner can maintain themselves will command a higher price and be more desirable to the majority of potential owners.