As Anaris said. Wudenkin is in the middle of the map. So anything that wants to get from anywhere to anywhere is basically garanteed to pass around it.
I know you probably felt pretty good about yourselves, everybody always thinks their success is 100% self-earned, but fact is, you aren't exceptional. There was 1 realm that was more central than Bara'Khur. Who was that?
Fronen.
Oh right, it's dead now. Killed by the rogues.
Diplomacy has nothing to do with how central realms are faring. BK being allies with the whole continent or at war with the whole continent amounts to the same. You said it yourself, Angmar can't send an army at BK, or else its own regions will get overrun. That also means that your claim that you could have done the same thing with priests is completely unfounded, because, again, you need those nobles to defend your regions.
Before a bunch of us went "why not, let's do this Mordok thing", we did try to reach out for military cooperation. But we couldn't send our army more than 2 regions away from our capital, and neither could our neighbors.
That Angmar *could* connect with its neighbors and collaborate with them is proof in itself of being a cushy coastal realm.
Note to the devs: I'm not really asking for anything to be changed regarding coastal/central realms and rogue behaviors, just pointing out the blatant survivor bias going on here. They are clearly believing that their results are 100% self-earned, and that any difference in results between them and other realms are 100% on the other realm's players' fault. When really it's just bias from their privilege.
Ok, maybe not.
This being the case, maybe it is time to abandon Bara'khur and move to a coastal realm.
Problem is, most of your existing nobles would not be received well, so you may want to just dump the existing ones and start some new ones.
Like advies, they are only characters that are quickly replaceable with a few just minutes of time, right?
Yea, I don't think "literally hollow out Beluaterra by carving out all of its central realms" is really a good long-term solution, you know?