True but we're talking about what happened fifty years back. The leaders of political parties in East Bengal were progenitors of the idea of Pakistan from the outset and were its early leaders (
Huseyn Shaheed Suhrawardy from the Muslim League became one of the PM's of Pakistan early on). Here's an old video from the fifties (CBS' Face the Nation) showing him answering questions like a true diplomat. Interesting in that he considers damming of rivers in India as the 'very worst form of aggression'.
Today Pakistan and Bangladesh are two brotherly countries joined strategically and militarily (the two defense forces of these countries are far more friendly and have important strategic ties than most outsiders realize, and then both again have deep ties to the Sri Lankan defense forces as well).
Even though Sheikh Hasina's administration is secretly working to whip up anti-Pakistani feeling in Bangladesh - its citizens are much too clever to dupe like this (especially the new generation). They know who their friends are as a country in the immediate neighborhood (South Asia). The future strategic direction of Bangladesh' foreign policy is (and always will be) decided by the Defense establishment, not by political parties like in India.
Bangladesh is also more or less stable internally (less so than India because of size). But most of all the people in Bangladesh consider freedom as their important birthright and they will not trade their freedom for any gain in GDP or better living condition under any master.