You’re right, especially for those who want to build their own land, situation and setting, fitting the armies of the people who take part in the campaign, the realms offer a lot more freedom. A blank slate, basically. I just don’t know how many will be willing / able to put in the extra effort to make their part of the world rich and evocative. May be easier for many to use some part of a more developed background to build on. AoS may get that, but it’s still a long way and, I must say, I don’t see much development in that direction. Still, the fan-made maps here in the forum are much more specific and interesting than anything GW came up with for at least parts of the Realms. Makes it quite difficult for less experienced world builders to actually get some traction in their sandbox. Which may be another reason why the narrative gaming is still lagging behind. Few people seem to feel at home in the Realms yet, myself included.