Axordil, this is a great question -- I wish I knew why...
My quick, off-the-cuff answer would that religions are always part of a larger society and history, in the context of a government and an economy. Many of them have said, per the divine, that certain injustices and inequalities should be reformed or abolished (divorce laws for Christianity and Islam, equal treatment for women and minorities per St. Paul (and Jesus, by example), the acceptance of female clergy in Christianity and Manichaeism (although most surrounding pagan religions had female clergy...), the abolishment of differences of caste in Buddhism -- I am sure there are other examples.)
In practice, however, these moves towards tolerance tend to be first-generation and most visible against the religion's historical context. Some religions maintain their example of tolerance (i.e. Buddhism and caste), but many adapt to local conditions over time. (Of course, of those local conditions can include a press for equality of the sexes
No religion, no matter how much it points to tradition, maintains itself unchanged -- it would die if it attempted to do so.
-Kushana