Isn't India as a country much more diverse than China? I mean I realise China is diverse too but in comparison. Putting a heavy yoke on a diverse country sounds like a recipe for rebellion.
India has 20+ languages with atleast one million speakers. China has one common uniting language Mandarin. I speak 3 Indian languages, yet when I moved to a new state for work, none of those languages help me while communicating with locals.