I think the benefit to the nation (I agree that there is a benefit) is really quite minor compared to the immeasurable loss - not to mention the inevitable anger - that policies like these would cause.

Keep in mind I still think all state level affairs should be in that state’s language.

This never really works out though. If you are in the presence of a dominant language pushed by the state, two things can happen - either the dominated language is prioritised by a state mechanism to encourage true bilingualism, or eventually there is enough discontent that something bad happens (see: Catalonia, historically - Basque Country).

The way things stand right now too, there is absolutely no incentive for an immigrant to urban Maharashtra to learn Marathi because everyone speaks Hindi, and Marathi is not actively pushed by any state mechanism. There are families (part of my own family) that have been here for several generations and do not speak a word of Marathi.