It's true that it will run with low requirements, but it will do so much more slowly than Civ IV, at least to launch - it's more processor-intensive than RTS or Total War games of the same age on my machine.
Surely most of the Total War games' depth is in the wargame aspect? The diplomacy is more sophisticated than in Civ V, but then it's more sophisticated than in Civ IV too. By contast city management is heavily simplified, at least in Shogun 2, where you can't build settlements, there's only one resource - wealth - and happiness is controlled merely by changing the tax rate, like a simplified version of the classical Civ system. The main strategic consideration is imposed by the limit on building construction slots in each city.