Speedo style bathing suits for men

These seem to be favored by European men especially although I have seen American men wear them too. IMHO these should not be worn by any male over 12 unless the male is a diver or swimmer participating in a competition. A cruise director on a cruise I was on said "Gentlemen, if you look down at the Speedo and you cannot SEE the Speedo please do not wear the Speedo." Why would a man want to put his assets or lack thereof on public display like that? Do any of you know a male who wears these who can explain why a man would choose this kind of bathing suit?