Denmark was THE senior partner, yes indeed. To a point were Norway actualy should be considered only a colony.
But you failed to grasp AW's point:
Norway was EXTREMELY important to the King of Denmark, because his heir would automaticaly became King in Norway as Norway was a heriditary kingdom. This was then heavily used to persuade the Danish nobility to elect him king in Denmark (an elective monarcy) also
Thus the incistence of the Danish kings on the name Denmark-Norway
Actually so important that Norwegians were often made excempt from taxes levied in Denmark and the Duchies as it was feared that it might provoke a Norwegian revolt.
That would remove the possiblity of a peaceful succession in Denmark due to it being a hereditary kingdom with a nobility that wasn't afraid of dethroning the King by renouncing its allegiance.