The idea of a pan-Indian lingua franca is violent. The question is not which language must be the lingua franca, but why any one language must be. The most common answer is that Indians need a common language to communicate with each other. But what is conveniently forgotten is that any lingua franca expands to become the one and only language that ultimately prevails. As I write this, I myself find it next to impossible (even a major waste of time) to write in two languages.
We are also made to conveniently forget that we need to alienate ourselves from the people closest to us to support an all-India lingua franca. For example, elite Kannadigas who think India needs a common language also necessarily give in to the violent idea that it’s okay for them to divorce themselves from tens of millions of Kannadigas. Let the idiots catch up if they have what it takes, or let them be wiped out by ‘survival of the fittest’ – this is the unstated feeling we have for our own brethren.
Patriotism is the offered justification for this violence, but the real one is simply the insatiable desire to get ahead of others in the race for material resources. Far, far non-violent than this is to have state-level lingua francas. That is, Kannada in Karnataka, Tamil in Tamil Nadu, Bengali in Bengal, and so on and so forth. Of course this does not eliminate the violence entirely, but it reduces it by degrees of magnitude. There is no perfection in the material world; the question is whether one is moving towards it or away from it.