I've often said that apparel makers are being pressured behind the scene by some unknown forces not to offer any form of men's clothing that may be perceived as "Gay" including speedos, short shorts, and snug fitting jeans.
Market forces alone cannot account for the current monopolistic style of jammers and knee length shorts. Without any variety, the market cannot be used as an indicator of preference.
I have sent emails to a lot of retailers suggesting they offer the old style shorts and swim wear and they have responded favorably. Mysteriously however, the products have yet to materialize on store shelves and it's a case of the "Status Quo".