I think you are indirectly trolling and your patronizing (feudal?) tone may be off-putting toward a lot of Bangladeshis here.
You say you're not a hate preacher but your language should be where you start seeking answers and remedying issues.
For starters - using words like 'Pakistan took in extra baggage at the time of partition' or 'Pakistan took too long to separate that region' is not representative of facts. Pakistan was a union and West Pakistan was not in a position to separate anything because majority income was coming from the East.
'Pakistan' was not supposed to be in a controlling situation when East Pakistan (agriculturally more productive at the time) was generating lion's share of GDP, yet were only allocated 30% of budget and 30% of foreign aid (see first video above).
There comes a point when immature, short-sighted and unequal behavior like this comes to a head, giving rise to questioning of status quo and talk of secessionism, and that is exactly what happened. Add Bhutto and Yahya's ham-fisted 'slash and burn' tactics, as I have mentioned above, then you have perfect conditions for secession being a success. Please blame your forefathers for this.
There were as usual more educated people and middle class intelligentsia in the East rather than the West. It is not true they wanted to separate from the get go, unlike what you are insinuating (people in the East were not 'gaddars' and did not premeditate secession). They expected maturity and equal representation with equal taxation which did not materialize in the union govt.
East Pakistanis expected to be Pakistanis on the basis of equal opportunity, equal distribution of wealth per capita in both wings, democracy, modernity and secularism - which simply did not happen. What did happen was spread and persistence of existing feudal power structure (from Punjab and Sindh) through the military. In military for example, Bengali popualtion was less than 10%, due to persistent West Pakistani nepotism and top-level leadership paranoia.
I believe Islamism (Islamic fervor) does not match culturally to the average Bangladeshi mindset while the opposite is rather true (and is a cultural construct and part of society) in Pakistan. Those two differing mindsets (and some say - refusal of West Pakistanis to accept East Pakistanis as equals in govt., in society and in academia) were unfortunate fissures that never got bridged, some would say more starkly toward the late sixties. Add to this the horrific formula of corruption and alleged nepotism in every societal sphere in the West, then you have toxicity that simply could not have been overcome in spite of best efforts on both sides.
There was also a section of Pakistanis (in spite of the West enjoying the lion's share of the wealth and development) who made a loud proclamation about making Urdu the common national language and imposing it on Bengalis, which did not go over well at all. Indians knew far better in their own country and left languages alone, making English the lingua franca.
The straw that broke the camel's back was when there was a devastating
cyclone in the East in 1970 and Pakistani govt. did precious little to send aid to the afflicted. That hardened East Pakistani attitudes about secession even further and the Sheikh was able to garner massive support for his ideas.
So - yes, screw-ups of massive proportions.
On a cultural front, the the first initial of Bengal 'B' was not even a letter in constituting letters for the place names making up the word PAKISTAN. The names of the five northern regions of the
British Raj was :
Punjab,
Afghania,
Kashmir,
Sindh, and
Baluchistan.
And when you say finally say Bangladeshis hate Pakistan, that is farthest from reality. In spite pf all that has happened, go see a cricket game between India and Pakistan in a Bangladeshi stadium sometime and make your own conclusions on who the crowd is supporting.....