For the same reasons that co-terminus Pakistan of the present chooses to shed its "kafir" Hindu and Buddhist past to declare itself an Islamic Republic instead of honoring the rich history of non-Muslims that contributed to the land.
The answer is that Religion based politics is a cancer. Pakistan has been a victim since Zia, India has its own Zia in Modi and Yogi.
Doesn't stop Pakistanis from singing praises of their country, where both good and bad exist including religious and sectarian politics. Why would India be any different under such circumstances?
We love India for what it stands for and what it was created to be, not what it is becoming due to the actions of these religious morons! Obviously most of us want India to be what our founding fathers envisioned for India, and I reckon most Pakistanis would prefer Jinnah's Pakistan than Zia's.
But instead here we are.....