This article explains an interesting feature of the Mughal Empire that led the nobility to build more tombs than palaces:
Since land could not be handed down to the next generation, there was very little incentive for the Mughal nobility to build palaces or the kind of ancestral homes that are common in Europe. The one exception to the rule, however, was for tombs. Tombs would not revert back to the Emperor. Hence the many Mughal tombs.