Accepting a nations capitulation as it is now (one city remains), is kinda screwing yourself.
You end up with almost always more negative diplomatic, economic, tech and resource effects.
If the capitulated nation, were to become a permanent ally, unless for breaking any of the 50% restrictions, it would actualy make it worth while.
Feel free to argue your position, pro or contra
edit : +
A benefit from seperating them could be that you could capitulate straight from the start, or a bit later.
Since surrendering isn't actualy a tech. But a sence of reason for survival.
You end up with almost always more negative diplomatic, economic, tech and resource effects.
If the capitulated nation, were to become a permanent ally, unless for breaking any of the 50% restrictions, it would actualy make it worth while.
Feel free to argue your position, pro or contra

edit : +
A benefit from seperating them could be that you could capitulate straight from the start, or a bit later.
Since surrendering isn't actualy a tech. But a sence of reason for survival.