Little headcanon that it started as just Maul and grew into a bit more than it: He doesn't use rings.
He doesn't mind jewels or any sort of accessories, necklaces, bracelets, earrings or even piercings. But rings are the one thing he avoids to use, mainly because of his lightsaber.
It's not exactly a problem, but lightsabers, specially one as long and straight as Maul, don't exactly go well with the rings if they're on the hand being held or come in contact with it. He has to have quick and unrestrained movements to literally not chop his own arms off.
You could say it's a problem for every lightaber user, but not for the jedi, specially before the war started, only after it actually became a problem. Before it was not bad to get a slightly off angle or not be as fast as you need because the lightsaber got stuck in a ring, but once the war started and a misguided strike could mean your life, a lot of the jedi let go of rings or after a lightsaber loss, modeled their new ones to match with the form of the rings and still be able to use them.
That is talking about standard, one blade lightsabers. Two lightsabers users do not use rings at all and they might even avoid too loose bracelets as well for the constant changes between the blades and the movements.
Temple guards did not use any sort of jewelry for the same reasons, too risky with the chance of getting something stuck or burned by accident.
As a result, simpler, smaller and tighter accessories are more popular. Tiny earrings, tight necklaces and anything with less chances of causing problems in the middle of a battle is the go to.