If you and your partner/wife/husband/boyfriend/etc both play Utopia, wouldn't it make sense that you'd both want to play in the same kingdom so you can help each other? (just like friends on different sides of an ocean can help each other's province) I think that many couples will quit if they are no longer able to play effectively in the same kingdom.
loki EQ's comment about NM is a very good argument. The introduction of changes to the rules (as enforced by the server) in the middle of an age doesn't just disrupt his kingdom's strategy. Bishop, you have played in organised kingdoms and should understand what impact this has on kingdoms. Let's say we have a couple in our kingdom who both play A/M. One is tasked with MS coverage (he/she picked mystic) the other (Non-mystic) is in charge of Greed coverage. These changes would severely disrupt the kingdoms plans because they can no longer target a province which was recently targeted by the other. This makes it very undesirable for kingdoms to have couples playing in them.