I'd rather go with encouraging people to have higher density. Reward realms if their density is higher than the average.
I was thinking this too. Rather than threatening people with the big stick of hitting realms with some negative force, rather reward realms in some way for having a more desirably density.
I do have some growing concern for realms going "well, we've got our regions, why bother invading the neighbor?". And, well, everyone doing that, because given how many nobles all realms have, in most cases, realms would surround themselves with rogue regions if they aimed for a density target.
That's a real concern. I know of a few realms now across the game who are saying they really can't afford to take more regions, for various reasons connected to negative-impact mechanics around density and realm-size.
However, people also do need to be a bit more imaginative in understanding that you don't always need to set a goal of taking land as the objective of a war. It should be possible to fight wars without any land changing hands if you set other objectives to decide who wins (for example, the realm that extracts the most ransom money from the other; the realm that wins the most battles in a set period of time; who takes the most prisoners in a set period of time; etc). Of course, the problem is that objectives like that aren't as rewarding as changing the colour of regions to your realm's colour. Partly, that's the fault of the game for not having any other ways of winning wars that are as rewarding in ways supported by mechanics; and partly the fault of player attitudes that nothing compares to painting the map.
