It's partly Shakespeare's own times. Go back to the 11th century, and the monarchy was elective within the late king's close relatives. Formally encoded, immutable laws of succession were a creation of the late 17th century. In between was an odd time, where the monarchy was basically successive by primogeniture, but this could be overriden when it seemed necessary, a situation asking for some deadly arguments to follow, as sometimes they did.

But partly, yes, it's the mix of times that went into the play.

The thing is, though, that I don't see any of the kind of cognitive dissonance you're describing here in The Merry Wives of Windsor.