Indian weapon against Pakistan: Urdu/Hindi

Re: Indian weapon against Pakistan: Urdu/Hindi

Why should a Pashtun or a Tamil have to learn UrduHindi? Why not just limit it to the Hindi belt in India and Karachi in Pakistan because these regions are the only ones who speak it as mother tongue? I have a few friends originally from Chennai, Tamil Nadu and they feel this way and non-Urdu Pakis feel the same.