It was a bit of an intellectual exercise to attempt to answer this question, but here's a response: Mike Levy, the 80s/90s infomercial host of Amazing Discoveries. The OG straight RichSim.
This is pretty much it: authenticity. People loved Richard bc he seemed sympathetic – even with all the theatrics (sequin shorts included). Simmons and Mulvaney are lightyears apart to older people – one seems ridiculously fake and one seems sadly sweet. But maybe that's not so for the younger gen. Maybe Mulvaney is sympathetic/authentic, despite his theatrics, in the same way those older of us found Richard Simmons authentic despite his theatrics. I'm trying to tease apart the difference between the two. Maybe someone gen-x or older can ID this distinction. Why is Dylan so off-putting compared to goofy Richard? Is it all about the gender proclamation?