Some people like their realm, despite the lack of battles. Yes, changing realms and seeing some real battles will probably be best for your H/P, though.
No, you may not be able to get 200+ in every realm, but 150 isn't exactly poor. If you're getting less that 100, you're probably getting ripped off. (Or you're one of those 3 realms in the entire game that have "enough" nobles already.)
It doesn't take an entire army to go monster hunting. 3 or 4 nobles will do. And any realm that is at war will normally be thankful to a friendly neighbor that can take care of a random monster group that is bugging them.