In general, trends in scholarship (in social sciences) tend to be affected by changes in overall attitudes in society. This is true with respect to views on the idea of "women's English." In the past, it was simply assumed or asserted that women spoke differently than men. The differences were generally described in ways that put women in a negative light. Women's language supposedly showed the women were weaker and less assertive than men. This was in keeping with accepted views of women in society.
More recently, however, scholars have looked more critically at these assertions about women's speech. Many have come to claim that there is no empirical basis for most of the claims that women speak differently than men. In this way, the more modern view of women's English is that there may not really be such a thing. It may be that people have perceived women's speech as different because of their commitment to the idea that women are inferior.