My language has a rich history, where as yours as you stated is the Haryanvi language doesn't even come close. I can chest thump all I want, I have the right too. Bengal has been through enough turmoil because of pride, rebellion/political strife has always been a component of Bangladesh and Bengal. We created our own militias, young boys from the age of 11 partaken in guerilla warfare. These men are now older than you and I.
@maroofz2000 can talk about this.
Furthermore if Persian was to be incorporated from the get go, there would be no problem. Iranic academics/scholars recognise Bengal as the easternmost region as a heavily persian influenced area and consider it part of the persian world in some respect. Arabs weren't the invaders, it was Turkic or partially Turkic races.
However Bengalis are still TOO proud of their native culture, only some people admire external influences.
http://www.iranicaonline.org/articles/bengal
In addition a whole book as has been written by Richard Maxwell Eaton of Hudson Cress.