No one can force Akbar to do anything. :)
Try to analyze this in a different vein. Akbar did what he thought right. And the power which HK got was due to her own qualities. Not all women were like her, and that's why she is still remembered with great regard. And Akbar was a remarkable man to give such freedom to his wife.
Hope this helps some what. If you read the link which i gave above you will get it more clearly. Please feel free to continue the discussion, until you get it clarified / satisfied.