India is a place where there is a vast diversity in terms of Religion, Language, cultures, food, music. It is also known as a subcontinent. But what if we had only 2-3 main languages and cultures? That would have made it a lot easier to communicate and relate to things all over the nation. Had there been one main religion there wouldn't be religious politics.
IMO if we did not have such a great diversity, India would have developed way faster than it is today.