It's a very debatable subject, there are those who feel they trust their intuitive sense enough to trust the connection they have with those in attendance. To be able to play with their backs to those in Meditative states and feel comfortable with not having to observe.
I feel many musicians/ therapists prefer to display the front of the gong towards those in attendance for the visual effect. You might think that truly the gongs would be the other way around, less glitz but easier for the gong player who would prefer to play facing those in attendance.
Sometimes i sit and think, with the playing of one of the larger Paiste instruments, a 60 or 80 SG. How the sound dispersion would be, with for instance the gong not faced directly towards those in attendance, but facing to the side. Given the size of such an instrument, i doubt there would be any lack of amplitude, and the Gong player would have great visual coverage of those in relaxed states. Some people feel they need to observe, and with good reasons. And again some will check in on those in attendance periodically. I guess its all about practicality ultimately, what works for yourself.
Kind regards
Paul.