I see it the complete other way round.
Bruma makes for an OUTSTANDING AD spearhead to quickly invade the north. And I've observed the yellow zone chat often capitalizing on exactly that. They have single dudes ride there and make way for the zerg.
Vlastarus and Cropsford are often ignored until after the fringe keeps have been sacked. Both villages are just too far away from a lucrative keep to make for a good blitzkrieg base of operation. Especially Crops with that f@#$/ river. Wtb ferry.
There's indeed really only the AD home keeps close enough, which are only important with scrolls. Once AD see the villages flagged, they know exactly where you're gonna go. With Bruma, you have Bleakers, Chal and Ales as important targets, and Dragonclaw as a nearby more permanent base.
imo you should only be able to respawn in keeps that are connected to your factions starting locations via an intact transitus way.
If a keep is cut from porting it´s also cut from respawning.