This game is indeed more engaging when you are involved in a war, but when you become Ruler you are inclined to try to protect your realm through peace.
I don't want to derail this thread, but what about limiting the number of other realms you can have an alliance/peace/neutral with? This would mean that by default, you are at war with more realms that you are at peace with. This would also fix some of the very long boring wars that are a wandering gang up on the next target.
I think when you introduce too many limits into the game, they limit creativity. We all agree war is the good part that everybody enjoys, but it's also fun to see what other creative things people come up with. Also, there will always be situations where the limits inhibit players in some unforeseen way that's not intended.
