Just double checked. Looks like beta-canon from the novels. Interestingly, according to Memory Alpha, the first episode or two with Bajorans in TNG had all the male Bajorans wear the earring on the right and all the female Bajorans wear it on the left, but right ears for both sexes became standard pretty early on. The only other named character that wears it on the left is Lt Mura in PIC.

That's a great explanation. Let's go with that.

Worf: "Our gods are dead. Ancient Klingon warriors slew them a millennia ago. They were more trouble than they were worth."

To give a more serious answer, Bajorans seem very theocratic and I think most of them would fundamentally disagree with the concept of a secular government.

Bajor exists in a weird gray area since their religion is in some ways literally real. In some ways the Bajorans are like the Vorta and the Jem'Hadar. Their "gods" are provably real, they interact with them regularly, and they have demonstrated to them that they have what seem to be supernatural powers.

Also, critically for the Bajorans, not only are their gods real, but their demons (Pa Wraiths) are real as well. And that opens up a whole other philosophical can of worms. In a way it reminds me of Warhammer 40k. In that universe, religion isn't irrational. In fact it's completely rational. Because Chaos is real, and it will fuck you up if you aren't religious.

One of the Bajorans serving on Voyager wore an earring. Gerron, the young former Maquis that was part of Tuvok's boot camp in "Learning Curve" had to give up his.

There's also Tabor from "Nothing Human", and Tal Celes from "The Good Shepard", neither of whom wore the earring on screen in the four total episodes they appeared in. Tal also had her given name before her family name, which is not the Bajoran tradition.

Even Seska didn't wear the earring when she was still undercover as a Bajoran, and likely could have gotten away with it thanks to her closeness to Chakotay.