I recall learning English/Hindi grammar as a kid and wondering on the futility of the entire exercise. I asked my teacher, "What is the point of learning grammar when I already know how to communicate with you?" My teacher did not think it was an intelligent question and basically brushed my concerns aside. Because of that unsatisfied curiosity, I did not take much interest in learning grammar afterward as is evident from my writings
Later on in my life, I watched a TV interview of a gentleman named Noam Chomsky. Back then, I did not know that he was a famous linguist. And guess what! He was talking about the exact same thing I wanted to talk to my teacher about. He was basically saying that natural language is something we do not learn; we are born with this ability. Our intrinsic ability to recognizing patterns in the speeches we hear as a kid forms the basis for us to master a natural language like Hindi, Bengali, English, etc. later.
I am a big fan of Sanskrit because this is the only language which is spoken across entire India. However, Sanskrit is not a natural language. Natural languages like Hindi, Bengali, English, etc. follow context based grammars. On the contrary, a Sanskrit sentence is produced by application of generative grammar which is similar to formation of a statement in a computer programming language. In brief, Sanskrit is a complicated language and therefore we cannot expect everyone in India to learn it but we should expect our scholars to learn Sanskrit. Sanskrit should become our national language. All official communications should occur in Sanskrit. This includes dissemination of lessons at schools.
As far as regional languages are concerned, there is nothing wrong with them flourishing side by side Sanskrit/Hindi. We just need to replace English with Sanskrit. That is all.