I've only played a few games so far on varying difficulties, but it seems that after successfully taking an enemy city, there is little strategic value in holding the city.
I suppose an exception would be to gain access to a new resource. But, it seems the enemy's cultural influence will remain in the surrounding tiles for such a long time that your own culture will take forever to expand your borders around the new city. So in most cases you are left with a single tile, and your empire doesn't have much new land.
Plus you have to factor in the cost of stationing troops in the city to keep order, and the city maintanence penalty. Honestly I've never just destroyed a city, but if you do, does the enemy culture still remain in the neighboring tiles?
I suppose an exception would be to gain access to a new resource. But, it seems the enemy's cultural influence will remain in the surrounding tiles for such a long time that your own culture will take forever to expand your borders around the new city. So in most cases you are left with a single tile, and your empire doesn't have much new land.
Plus you have to factor in the cost of stationing troops in the city to keep order, and the city maintanence penalty. Honestly I've never just destroyed a city, but if you do, does the enemy culture still remain in the neighboring tiles?