Rejected as unacceptable by who? Why should this be rejected as "unacceptable"? This form of government could only be "unacceptable" if was not in the best interest of the society, which brings us back to the common good again.
What you're really saying is that a dictatorship could serve the common good, but since it is not a representative form of government, it would not be serving the common good as well as a representative form of government would.
Not at all. For example, there are plenty of adults who would probably be better off if they let their parents continue to make all their important decisions, and yet that is properly rejected as unacceptable.
I'm surprised that I'm called upon to state here, of all places, that for a society to be fat, dumb, and happy (i.e. to have its "best interest" taken care of), but without freedom, is an unacceptable state of affairs. Next, I daresay, I'll have to break the news that Bill Clinton was less than entirely honest with the American people.