Though the leaders initially feared the formation of states on a linguistic basis later they agreed because they felt:

1. If we accept the regional and linguistic claims of all regions, the threat of division and separatism would be reduced.
2. The accommodation of regional demands and the formation of linguistic states were also seen as more democratic.

Both are correct

One of the most important concerns in the early years was that demands for separate states would endanger the unity of the country. It was felt that linguistic states may foster separatism and create pressure on the newly founded nation. But the leadership, under popular pressure, finally made a choice in favour of linguistic states. It was hoped that if we accept the regional and linguistic claims of all regions, the threat of division and separatism would be reduced. Besides, the accommodation of regional demands and the formation of linguistic states were also seen as more democratic.