True-India was never united- it was unified politically as a nation but its people never treated everyone fairly. Now prejudice occurs in a lot of countries but I haven't seen it more in any other country, its because of its size and population but more because there was never a common ground on which the Union of india was found. Just a bunch of states who wanted to join for protection. India should have been more selective then.
Even so after it was unified its people weren't. Reason being ignorance and arrogance. Even now most people won't know names of north eastern states, or their capitals, no1 makes an effort either. its shameful for a country.
At present I would say unity is decreasing even more but now its no longer a bad thing since the success of a country is being measured economically. nationalist and patriotic fervours are bygones and in the 21st century of globalisation all that matters is economic well being.
But just like a company cant have a bad sales sector, nations will need to bring up standard of living for the poor, allow fairer distribution of wealth.
India will have to follow suit and with better economic state it will be united as a country.