Why isn't swimming naked more popular than it is?

I've experienced swimming naked with a bona fide naturist group. It was wonderful. I'd hate to go back to trunks, yet my nearest swim, according to British Naturism [this country's largest naturist body], is about 30 miles away. Why don't more people clamour for these naked swims? Swimming naked at a normally public pool is a uniquely liberating experience which no one should miss. [unless you're ugly].