The growing nationalism is a good sign for any country, but some people are opposing it. What is so fearful with nationalism? India is a country where people are divided in many ways, based on religion, caste, language, areas. There is much diversity but unity in diversity is for what India is known. But it took bad shape when the politics grow up on these bases, political parties setup based on caste and religions.
If I say in one line- Nationalism is a cure for Casteism in Hindus, and Radicalization in Muslims.
The more feeling of nationalism grows in people, the more people will come together. This will end the politics on casteism, religion and will stop some NGO who gather money on these bases.