Ethnic divide creates ripples among Pakistani community

Re: Ethnic divide creates ripples among Pakistani community

Why do Pakistanis feel the need to have just one national language? In Switzerland they've been living together for hundreds of years, and they have four national languages: French, German, Italian and Romansh.
In India they have 21 national languages, which are all used for (local) official purposes and in education.
Why can't the same be done in Pakistan? Declare Pashto, Balochi, Punjabi, Sindhi, Urdu and Kashmiri to be national languages with Urdu as the "national link language"?