What changed?

Here is a paragraph from Ram Guha’s India after Gandhi (p.124):

The women members of the Constituent Assembly had come through the national movement, and were infected early with the spirit of unity. Thus Hansa Mehta of Bombay rejected reserved seats, quotas, or separate electorates. “We have never asked for privileges,” she remarked. “What we have asked for is social justice, economic justice, and political justice. We have asked for that equality which alone can be the basis of mutual respect and understanding and without which real co-operation is not possible between man and woman.” Renuka Roy of Bengal agreed: unlike the “narrow suffragist movement[s]” of many so-called enlightened nations,” the women of India strove for “equality of status, for justice and for fairplay and most of all to be able to take their part in responsible work in the service of their country.” For “ever since the start of the Women’s Movement in this country, women have been fundamentally opposed to special privileges and reservations.”

The quotes are from the constituent assembly discussions in the late 1940s.

What changed from late 1940s to late 1990s that we are introducing the women’s bill reserving 30% of seats in the Parliament for women? Who is to be blamed for the failure, if any? There is no discussion on these issues in Guha’s book (not at this point, at least). It would be interesting to know.