These areas don't have much detail to keep a low polycount mostly, Its quite obvious from many spots after all, the area around Hydlaa is totally empty. I don't think its going to remain like this, sooner or later we should upgrade the scenery of the game in general. Thing is, we are still limited from the engine and can't go all out adding things everywhere. If we added extra detail outside Hydlaa's gate perhaps it wouldn't matter too much, if we kept those things to be seen from Hydlaa's level though (on the map inside the city) it could result to some heavy lag.
In any case, a visual upgrade to the world should come, sooner or later.