In my humble opinion, this attitude is based on incorrect presumptions. Reason for the 1971 debacle was not that Two Nation Theory was wrong. Pakistan was supposed to be a Federation, such as the US. Indian politicians were sagacious and they adopted a constitution as early as 1949.
Gandhi asked a Dalit, Dr BR Ambedkar (aka Babasahib) to write Indian Constitution so that minorities should not feel deprived. Indian constitution was adopted in November 1949 with India becoming a Republic on Jan 26, 1950. It is a different matter that now BJP (a high caste party) wants to amend the constitution to minorities’ disadvantage.
Sadly Muslim League comprised mainly of landed Muslim gentry who are by nature autocratic. We had to wait unit 1956 for a constitution and to this day smaller provinces feel short changed. East Pakistanis also felt at a disadvantage. One must not forget that Mujib did not ask for Independence. His famous 6 points were:
1. The constitution should provide for a Federation of Pakistan in its true sense on the Lahore Resolution and the parliamentary form of government with supremacy of a legislature directly elected on the basis of universal adult franchise.
2. The federal government should deal with only two subjects: Defence and Foreign affairs, and all other residuary subjects shall be vested in the federating states.
3. Two separate, but freely convertible currency for two wings should be introduced; or if this is not feasible, there should be one currency for the whole country, but effective constitutional provisions should be introduced to stop the flight of capital from East to West Pakistan. Furthermore, a separate banking reserve should be established and separate fiscal and monetary policy be adopted for East Pakistan.
4. The power of taxation and revenue collection shall be vested in the federating units and the federal centre will have no such power. The federation will be entitled to a share in the state taxes to meet its expenditures.
5. There should be two separate accounts for the foreign exchange earnings of the two wings; the foreign exchange requirements of the federal government should be met by the two wings equally or in a ratio to be fixed; indigenous products should move free of duty between the two wings, and the constitution should empower the units to establish trade links with foreign countries.
6. East Pakistan should have a separate militia or paramilitary forces.
Accepting the above meant that Pakistan would have become a Confederation of two wings with a weak Centre. Governor of East Pakistan, Vice Admiral Ahsan was strongly against the military action and resigned in protest.
By saying that West & East Pakistan should never have been one country you are indirectly implying that India should not been partitioned at all. There was a strong Unionist movement in Punjab, NWFP under Bacha Khan wanted to remain in India and Jamiat Ulema Hind as well as Jamaat Islami were also against partition. Without the combined effort of Muslims of India including the Bengali Muslims; India would not have been partitioned; hence no Pakistan and no Bangla Desh.