Women in general have much more freedom in the way they can dress. There are also higher expectations and more unwritten rules.

Agreed, but on the surface of it one might think that given the more varied ways that women might dress, they need more rather than less written rules for women vs men to control the way they actually do dress (at FIDE events).

So, the logical conclusion is perhaps, no surprise, that FIDE don't really want to enforce a strict dress code, but rather want to promote the sport, and that translates differently into dress codes (or lack of them) for men vs women...