Well, if i put it right, majority in India would not be able to recall who Ali Azmat is but if you would ask them they would certainly remember "Sayyoni".
Not singing in India is not a loss for India but for him. There are many Pakistanis who got their fortune made by being in India. As for us, its good that our young lads get more opportunity if the competition from Pakistani based Bollywood singers gets reduced. Of course the people across our border got talent but it's them who are unfortunate for mixing politics with art.
When the Govt. of India chooses to deny a visa, it's for a reason. Indian Visa to Pakistani performers is a privilege to them, not their right.