In an ideal world, I would agree with Indirik.
However, currently - as Indirik is very well aware of - I don't want to put in the time or effort to dig up a great casus belli. I settle for... lesser causes for war, and I'll take the flak that comes for it.
And while I do agree that people get too attached to their realms, I understand that they do. It's about the effort being put in. Seeing that go sucks. I would argue for a game where we would wage wars in which you do not have to fear for the total destruction of your realm. Change the dynamics that way, from a playerbase mentality, and wars should come easier.