Answer:
One of the reasons was that the Revolution has begun in Boston. If you think of it Boston was the only place where the first steps of revolution were taken. Boston Tea Party, Boston Massacre, Bunker Hill, Battle of Lexington&Concord, And the first blockade of the Revolution, Paine wanted the readers to imagine themselves as the people who have started the revolution and have suffered the most to make the readers show sympathy for the Bostonians and come to their aid supporting the American Cause.
