I think the problem was ironically that the third film WAS too goofy.
You had a silly-sounding dude, in a ridiculous mask, who has this mysteriously and explicably loyal army of guys with no explained logistics (where are they getting their supplies constantly?), successfully conquering a city and holding it for months.
And why are they going to hold this city for months? So they can nuke their own base of power months later.
So little of it really makes sense the more you think about it.
You can't hold a city for months because an army that size would use up its supplies fast simply policing it.