Actually it wasn't quite a new trend to give away Hindu princesses to Muslim kings/prince in marriage in 1562.
I quote Jadunath Sarkar from his book 'A history of Jaipur' page 37 -
The giving of Hindu princesses in marriage to Muslim kings had been known long before the union of Akbar and Bihar Mal's daughter. As early as 1176, we read of the queen of the Rajah of Uchh (a town now in Bahawalpur State) having affianced her daughter to Shihabuddin Ghori. In more recent time, a Bharti Rajput princess Naila (the daughter of Rana Mal of Dipalpur), had been married to Salar Rajab. She later became the mother of Firuz Shah the Tughluq Sultan of Delhi. More instances may be found in the lives of the Muslim kings of the Deccan.
But Akbar's mingling of blood with the Hindu ruling houses, of which this marriage at Sambhar was the beginning, stands on a different footing altogether from all previous instances of such unions. It introduced in its effect a complete revolution in the policy of the Muslim monarchy in India. In the earlier Hindu-Muslim marriages, the bride was thenceforth lost to her father's family as sully as if she had been kidnapped or killed. Her Hindu kinsfolk ceased to have any further communication with her or her husband. But Akbar's policy was to make such unions the starting point of a new order of relations in which his Hindu kinsfolk by affinity would stand on an equal footing with this Muslim father-in-law and brothers-in-law. They would hold their heads as high in his Court, differing only in that they could not dine with him, pray with him, or reciprocate by taking Muslim girls as their lawful wives. Thus the giving of a daughter in marriage to Mughal royalty, ceased to be a mark of degradation for the Hindu father within the Court circle and the polished Hindu society of that age, although orthodox Hindus still looked down upon it as a humiliation.
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