I share your outlook OP. The idea that a man buys a costly ring for a woman when they get engaged is clearly iniquitous, because it's not balanced. And it obviously emerges from all kinds of sexist history, such as the fact that when the modern concept of engagement rings was born, most women couldn't have bought their husbands a gift in return, or contributed to the ring themselves, because they weren't financially independent. Interestingly, when you look at eg royal engagements in the past, the couple would genuinely exchange tokens, because obviously BOTH of them were wealthy (a king would marry a princess etc).
Even the fact that women get and wear engagement rings whereas men do not is an inherently gendered behaviour. If I got married, I wouldn't have an engagement ring, for this reason.
.. .but, for all this, I have to remind myself that everyone can make their own decision as a couple, and it doesn't make any difference to us as individuals what other people choose to do. That's what's great about this subject. Unlike many others, what one couple choose to do doesn't make any difference to what others choose to do.
So if you see things this way, you and your fiancé can split the cost. Another couple can have the man carry the whole cost. And it's best not to interfere or comment on friends' etc choices, as it only leads to upset around such a personal and emotional issue.