I'm inclined to agree with Nekrage here. I have no problem with casuals and solo's having their place in the world, such as the beastmen lands etc, but when peoples cities are ALL turned into safe zones, it's changing the direction of the game significantly. I'd argue too much.
I would be happy with a compromise such as say......3/4 NPC cities across map which are classed as safe zones, and then player towns are restricted to the actual guilds (with obvious benefits over NPC cities).