You are quite right about this. IMO, this is due to the failure of the Hindutva right wing in the freedom struggle. Having failed to contribute, and being condemned to the rule of law under a constitution which was frankly abhorrent to them, considering the odious principles that it represented to them, they had to find a way out.
Their way out was to claim nationalism for themselves, and to use the worst personal abuse against the reigning establishment and political party, the Congress.
The Congress helped this along manfully by going into excess after corrupt excess,and turning people against them through sheer loathing of the morals and lack of integrity of the khaddar clad Congressman, and through contempt for the stark opportunism of their transmutation of Nehru's possibly heart-felt secularism into the gross kind of political manoeuvre that Arun Nehru represented. When Arun Nehru's counsel prevailed over Mohammed Arif Khan, secularism died in the Congress, and those of us who despised their corrupt habits found to our dismay that there were even lower depths to which they could fall.
Returning to the makeover of the bigots, they then staked out the boundaries of nationalism by pushing an extreme jingoist version as the accepted norm. Under this proposition, anything short of the will to destroy uncooperative neighbours was treason. Whether China or Pakistan, or even harmless, inoffensive Bangladesh, the 'other' became an object of hatred.
Take the case of Bangladesh; even with all the stupid posturing of the BNP and Khaleda Zia, and the harbouring of the most poisonous Islamist elements, and their launching into Indian soil jointly by the Bangladesh authorities colluding with ISI and the theocracy, Bangladesh never was more than a nuisance. The Sanghis converted it into a demonic land, people with pole-vaulters, and poured the full contents of their acid hatred onto the servants that they themselves used, who were supposed to be grabbing jobs and straining the infrastructure with their unplanned, unmanageable numbers - all the while conveniently avoiding mention of their own role in supporting this situation, and brushing aside the fact that even without Bangladesh illegal immigrants, the stress on jobs and the straining of the infrastructure had been present.
They also worked out, or allowed to evolve through trial and error, an effective way of subverting the constitution and its provisions. On the one hand, they work, continue to work desperately hard to capture the administrative high grounds, putting 'their' people in place everywhere, from the autonomous Film Institute to the supporting institutions of government, including the abolished Planning Commission and the judiciary at all levels, which they have had to leave unpenetrated as they didn't have enough educated and learned men themselves.