The Thalmor invasion was recent. They actually took Cyrodiil for a while, but the emperor and some men managed to get out. They got their men from Hammerfell back and managed to take back the Imperial City. And any logic would say war/invasion = bad condition. I tend to get the impression the Thalmor would carry out a pretty 'clean' war, if anyone would it's them. I imagine their troops would have been trained to fight quickly and skillfully, I expect the damage would be no where as bad had, say, the invasion been by Orcs.
