The mass exodus of nobles will cause some realms to collapse entirely, and I'm fairly sure there will be no mass influx of nobles to compensate.
See, that's part of the problem: Otherwise nonviable realms propped up by dual characters. If people move out, and spread out to other islands, then more realms will be viable, and viable because they actually have more than, say, 4 players in them.
I know I will not be among any such influx, as I have no desire to play on the other continents for various reasons.
What reasons? If you don't tell us, we can't know, and make any possible changes, if needed.
Also, if you haven't played on an island in the past two years, then realize that you effectively haven't played on that island at all. (Except for AT...)
I will be finding the game far less enjoyable due to this exercise of ignoring player feedback.
Not acting on feedback does not mean it's being ignored. We are here and listening. We're just, at this point, going to disagree with you.
If you want to stop players from having two characters in a realm to artificially support themselves, create a one character per realm rule rather than this overbearing and unnecessary restriction.
That only solves one, and minor, problem of multiple characters. Two characters with significant power in different realms are undoubtedly more powerful than in separate realms. If anything, an I'm not saying this is what we would do, I would force both characters to be in the *same* realm. This addresses the problems of unduly large influence, unbreakable alliance, unrealistic/unfairly reliable communication, etc.
And for a roleplaying game, where is the concern for the arbitrary violation of many player's long RP lines for the sake of this no-improvement change?
You're saying that you're not willing to slightly adjust your RP for the sake of a better, healthier game? That maintaining your two-character-on-an-island RP is more important than helping make the game better, and more active/dynamic, for everyone?
The point of this change is to help make the game better. More active. More vibrant. More dynamic. For everyone. If the players are willing to play along and give it a try, then I have no doubt that we can make this work.
