Here's Cessna's logic for not changing the design if their crappy wheel pants:

Mid 1970s: We are selling lots of airplanes. Why mess with sucess?

Now: We are not selling many airplanes. Can not justify spending any money on R&D.

Well designed wheel pants can make a big diference in speed for a full scale plane. The wheel pants on the Lancair Columbia are good for something like 17 knots. That's about as good as retracting the gear but without the weight, mechanical complexity, cost, etc.

cirrus