Every language that has separate terms for relatives is an impenetrable mess.
E.g., in English a spouse's parents are just that, parents-in-law. And the spouse's brothers and sisters are brothers- and sisters-in-law. That is it.
Let's take Russian. Each of the following is a separate term:
- husband's mother
- husband's father
- wife's mother
- wife's father
- husband's brother
- husband's sister
- wife's brother
- wife's sister
The inverse is also true. Your daughter's husband's siblings and parents have a different term from your son's wife's.
Very, very simple.
These are variations on the Sudanese Kinship category, and they are both arbitrary and complex: https://en.wikipedia.org/wiki/Sudanese_kinship?wprov=sfti1
Every relation had a different name, including if they are older or younger than you, and if they are male or female.
Personally, it just feels like gendered languages just place men and women in different noun classes while non-gendered languages don't. But it feels weird to place the emphasis on the gender when the vast majority of things in the category don't have gender. It's all rather confusing and I'm not a linguist so don't take anything I say with high confidence.
[0] https://en.wikipedia.org/wiki/Noun_class
[1] https://www.quora.com/Why-is-the-french-word-for-vagina-a-ma...
[2] https://www.degruyter.com/document/doi/10.1515/gcla-2014-000...
Experience of learning some gendered languages makes it painfully obvious that it's a runaway effect, some kind of a mind virus. If 3 alcohols the wine, the champagne, and the sangria happen to use 3 distinct rules for declination in a language (and make you sound like a nitwit if you misremember one) something must have gone seriously awry. Partying hard cannot require such complexity.
If there would be some usefulness in that distinction, you might argue that it's as useful to assign woman together with one of the alcohols, man with a different one, and a child with the remaining one. To me it looks like standing the issue on its head.
Languages are optimized firstly for the people that speak it as their first language. There are some suggestions that in some cases, a group of people that learned a language later in life can influence the development of the language too, but it's not the primary mover. When you are a L1 speaker, the grammatical gender doesn't really require any cognitive effort in most cases.
And there is an actual benefit in a conversation between two proficient speakers: redundancy. If you're in a bar that serves those three kinds of alcohol, if you were speaking a language without grammatical case, you'd only have to miss one word (the alcohol) to misunderstand the order. If there is also a gendered article, you'd be able to mostly understand the order even if you missed the alcohol.
They also let you communicate more complex ideas more easily but letting you use two or more pronouns in parallel without ambiguity. This sentence is confusing in English, but makes total sense in gendered languages: "Hand me the wine and the sangria. It's in the tall bottle, and it's behind that door"
Truly optimized? I'd rather say: having arrived at a random local minimum.
The anecdata I can offer. The people who speak this (non-fictional) language as their first one, struggle very much in the beginning. It's far from being given for free: children are not immune from opportunity costs.