It also allows for more variety in the interactions. If you can interact with them in the camp, they can discuss the questline for that region as it progresses and, depending on the story, possibly have a larger role by accompanying you at some point (not as a companion, more like a "they show up in the climatic scene/dialogue" kind of thing). Then, when you come back to the Keep, there could be an additional set of interactions.
Well, those things could happen. I guess it's mostly just that I don't think those things happening require you to see them in camp and seeing them in camp doesn't confirm they will happen.
I'm just still really skeptical about NPC romances, I guess. People list a lot of things they could do, like showing up to help out on missions, but they just as easily could.. not do that? I mean, they could pretty easily just be slightly better versions of ME3 NPCs. I expect them to have about the same amount of romantic dialog as other LIs and to give you quests, but I don't know if I really expect as much extra stuff as people are suggesting. It could happen.
I admit, though, that I could be letting bias taint my view, because I'm just never going to like a romance plot as much when I can't take them on quests. It's really important to the dynamic, to me. NPC romances, at best, can be "this is pretty good, but would be better if they were companions" to me.