I think there is a need for some sub-nationalism among the people of bihar.

Atleast regionalism is better than caste politics, there is a need of sense of competition among bihar people and the govt, with the other states, especially non hindi belt states.

Why it isn't already there, given all the hate bihar gets from people of other states?

This might also generate some respect for Bihari culture and languages from the young population, most of them aren't even taught bhojpuri/Maithili/magahi as their in their homes (those who don't live in bihar). They always associate Bhojpuri with silly sexualised songs and funny accent.