and, in any case, deciding that to be “free” a woman has to remain a virgin or never have a child is a limited vision
I think it's a limited vision if this is the *only* way considered for a woman to be free, but historically (and currently), it's been a valid, interesting and frequently made choice. In Katherine Kerr's "Daggerspell" books, Jill (an apprentice sorceror) is horrified to find that as part of her relationship with the man she loves, she is expected by absolutely everyone to be a good wife and have children. She rejects this, lies and tells him that she's barren and he should marry someone else who can bear him children, and goes off for a life of travel, study and adventure.
In a society without contraception and an expectation that women take care of the children, (heterosexual) celibacy may be the only way for a woman to be free in that sense, particularly if she doesn't have the wealth or status to pursue her own desires on top of providing for her family and caring for the children. I'm not sure why you don't like this idea - I can see that setting the world up this way could be a failure of imagination, but using fantasy as a commentary almost every culture in our world is certainly not invalid, and basing a fantasy society on almost any historical setting without getting handwavy over contraception and childcare is going to have this option looming large for any female character who may want other choices in life.
Except historically, women did have options in some places and times. Women in towns in northern Europe had an amazing degree of freedom in the high and late middle ages, which is what most fantasy is based on; in these situations (townswomen made up what, 10-15% of the overall female population?) they were actually legally more free than independent noblewomen; they'd be taught a trade from puberty, and if they married a husband in that trade they could help him, but if they didn't they could run a business independently (I ran across records of unmarried English tradeswomen who managed to support bastard children and send them off into respectable trades themselves) or, if they married a husband who did something different, were legally granted autonomy over their own businesses, to the point where their husband had no say over their wives' business transactions.
So. Granted, it wasn't done a ton of the time, but during a time-period fantasy chooses to focus on, a not insignificant population of women didn't have to make the choice between children and independence.
Yes, the same is true in the Japanese merchant class of the Edo period to some extent, and I find it a very interesting part of history, and highly relevant to microbusiness today (especially in Third World countries). On the other hand, it's not something a woman can choose in the time to which you refer - it's a class into which she is born.
I have two objections to it:
1) Fantasy worlds not based strictly on historical molds have fewer excuses. If the world accepts homosexuality and says that women can, for example, be queens and businesswomen and mages, why the fuck do they have to be virgins in other professions? You'd think female soldiers would be possible- adjusted for weapon size and physical strength- the same way female mages and rulers and businesswomen are possible, and there's no need for silly rules about sexuality.
2) The emphasis on virginity and lack of children in worlds set up this way pretty much guarantees that the focus will be on young women, or teenagers. What about a widow who has borne a child, so definitely isn't a virgin, but still wants to enter a male profession? Why should she be forbidden (by the author) because of the silly, silly emphasis on virginity?
And possibly also:
3) The author lets men do whatever they like, sexually, but punishes her female characters for expression of it- as if every single sexual act ever done would result in pregnancy. I would think that use of hands and tongue could satisfy, but many authors prudishly forbid women even that.