I believe this add to the realism. Deploy an army into the city's townsland, and you have surrounded the city. No way someone is coming in or out of the city without facing the enemy army.
I can attest to this. We have used this fact to great effect in several sieges, including the siege of Gelene during the war with Everguard and when we brought down the Raivan Empire. It is devastatingly effective, especially if the townsland is still fortified and the city in question is the capital.
