As you can see by my picture, this is a subject I'm passionate about. Haha. The idea of nude yoga turns me on, especially one-on-one with someone you're hooking up with... I have done that a few times, as "foreplay", in a way. And looking at pics of naked guys practicing or posing is def something I really am aroused by. A lot...
Only very recently have I had ANY idea of doing naked yoga myself, and that's after practicing since November 2013 at this point! I've had gay male teachers invite me, or talk about a naked class somewhere, but I just never found it to be something I "had" to do. I dunno. And I wasn't worried about the erection potential, as that's likely to not be an issue if you're seriously practicing, and "in the zone". If you're truly practicing, erections aren't happening because you're moving around too much. But I also practice in yoga pants, they really changed my practice in 2017, for the better, and I think it would take some adjusting to go from support to fully exposed package. I'd be worried about smashing my junk in things like cobra pose, upward dog, etc. I'm sure I'm wrong, as men clearly do nude yoga. And pants, shorts, or any article of clothing is a mere layer between your skin and the mat anyway...