Turning a bunch of regions rogue would have the same effect on player density as blighting them would, except that it would allow the players to then decide which regions to prioritize if they seek to expand instead of having it forced upon them.
I'm not sure I understand what you're getting at.
If regions are turned rogue, people will just take them back. Period. That is absolutely plain from the players' behaviour.
I fear the most valuable regions would be targeted first, leaving the crappy regions behind. Scorched earth warfare. Which, in the end, leads to a bunch of realms incapable of properly fighting each other.
If that were the result, then personally, I would try to make sure that things went one of two ways: either the whole worthless area got blighted, or the blight was able to be moved from the valuable regions in some manner.
I dunno about any of the rest of the devs, but I have embraced the maxim of We Do Not Hate The Players.
