The height of the TRI speedo generation, was when Kenny Souza made it to the cover of runners world magazine with his glam-rock star hair running up a sweat with wearing nothing more than a fluro yellow mankini speedo , six pack and Oakley razorblades. And he didn’t even swim as a duathlete!
The turning point was when triathlon wanted to get into the Olympics, all the extra rules came in…everyone had to wear the same kiwami, couldn’t pull the zip down half way, couldn’t show navel or run topless down the street for public decency etc. For better or worse triathlon grew up a bit to get on Olympic tv
I think to just blame the disappearance of speedos on federations and orgs isn’t the real story.
I think as the sport was in its infancy, we were considered some freaks you better didn’t bother with a dress code.
Once the sport got more mainstream, there was direct and outspoken pressure to conform to social norms, including ‘covering up’. Especially as the sport took off in more prudish societies such as us.
So as sponsors and families became more involved, there was more pressure to cover up, and then orgs came out with hard rules to avoid public conflict.
.
I was once asked/offered to wear running shorts during a race in rural America…. good times.