My experience is that war does not contribute to having a dynamic, active realm. Quite the opposite. A lot of talk is often steam rolled by war measures and justified by the urgency that war creates. In all of the realms I've played in, once wars started, I'd see this kind of thing going, and not only by rulers on a power trip, but by all ranks of nobility.
Hmm... my experience is usually the opposite. Realms at war have more messages, more discussion, more participation. Yes, it is almost all war-related. But the game centers around warfare, so I hardly think that's a negative.
Now, trying to cause trouble is often stamped on harshly during war times. I can agree on that. But simply talking, RPing, or discussing the war and the related strategy? I haven't run across that.