One reason is financial. At its peak the Mughal empire was the largest economy in the world. Estimated to be about 25% of global GDP. That's close to the position US occupies in the modern world.
Estimates for the Maurya and Gupta periods are significantly more speculative than Mughal estimates. We have reasonably good tax and mint records for the Mughals, whereas Maurya/Gupta figures rely heavily on back-calculating from population density. Is this what kids in India are being taught these days?
Mughal empire was collection of many wealthy provinces, which were wealthy even before Mughals. After assuming power most Mughal ruler did nothing but wasted wealth on countless vanity projects, unlike Europeans where rulers still funded exploration and innovation.