And I want to thank you for posting as you can't have a discussion without multiple view points.
Now as to the topic at hand.
We used to have a society with strict lines defining gender, not only in clothes, but also in jobs and other behaviours. Feminism has been a lot about crossing those lines with the goal of getting women seen as equals of men. It has also become somewhat easier for men to cross those traditional lines but is seems to be a slower process.
On the other hand, like others already posted, part of it is because the Feminism movement is not about women trying to be men but about having equal rights. Women trying to be men still have the same problems as the other way around. A woman with a beard has no easier time than a man in a dress for example. People still get upset and confused if you cross the gender lines.
What often leads to confusion on this forum, is that there are two kinds of people here, those that want to be the opposite sex, and those that want to cross the gender lines. Their behaviour might be similar, but their mindsets are not.
What has changed over time is where the gender lines are drawn, and a lot have become fuzzy, some don't exist any more.
We as a community still run into problems if we try to cross the lines that remain.
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So we should try and ask, what has made lines change, become more fuzzy or disappear in the past and can we use that?
I find that a hard question to answer.
Some of it has to do with having a reason for crossing the gender line, that ends up getting accepted by society at large, but that's far from the entire story.
Maybe someone else can come up with some good answers to this question?