My first impression upon seeing Dwilight island is this is People fight against Environment. (PvE as some players may call it)
To watch the lands grow and ebb is part of the process. Of course those players who open dark portals causing more problems to humans, if many realms do not like those players, they can simply ban them or put bounty on their heads for their troublemaking activities.
Frontier realms should have some frontier feeling to it. Maybe frontier realms can seek other realms help; for you guard the front against monsters and undead attack on their behalf. In this way, both frontier realms and non-frontier realms can benefit from alliance, just saying one of the many ways which can benefit us all. It is up to our characters to solve the problems. If you think rogue problem is bad and your realm need help, ask other realms. Call it mutual benefits 
The question, or issue rather, is not whether it is meant to have a frontier feel to it, I do think there is a point in that, but the issue is that I think it is driving away players by not giving them a chance to otherwise play the game. If a mechanic is driving away a player base, then surely it should be reconsidered. I know that I have felt less inclined to play due to the ferocity and unrelenting nature of it all, and it seems from talks in OOC that a few other players have felt the same, which I am sure was not the intention.
As for the help you speak of, the issue is that most realms are pressured, and the amount of nobles in the realms are not that grand, with that add the distance some of them would have to travel, they would come, fight a few battles, have to retreat, and it would have made no real difference due to the continuous swarms.
