Hakatan- I don’t think it has anything to do with need. It’s clear from the sources that they are allowed to learn Gemara, that’s why both the Rambam and S”A say they get sechar. But they still aren’t commanded to do it. So with no motivation to learn, they aren’t going to bend over backwards to engage in Avodas Hashem that they aren’t commanded to do and only receive sechar as eino metzuveh veoseh. You need to be internally motivated to engage in an aspect of Avodas Hashem that you aren’t commanded in.
For most of Jewish history, women were not educated, or minimally educated, in both Torah and secular knowledge, so additional Torah knowledge wasn’t appealing to them. Which is fine. They have no command do so. But as women become more educated, they have a desire to expand their Torah knowledge beyond what they are commanded to learn… and that is also fine. Because Torah is for everyone, men and women, that’s why they both receive sechar for learning it. Men have a bigger responsibility and therefore a bigger reward, but nothing is closed to women. If it were, if it were actually prohibited, they wouldn’t receive sechar for doing it.