Have you ever spoken to a 25 year old? People are not emotionally, and mentally mature enough to be parents at that age. And how many men in that age range are financially stable enough to provide for a wife and child?
Nobody said 25 year old women should marry 25 year old men. For most of human history women married up in terms of age for this very reason just as men married down in age for fertility.
Women should be getting married in their early 20s to men in their mid-30s. That's the way its always been. By 35 a man has built up his resources while at 20 a woman is still at her peak in terms of fertility.