Myself I never see strong force in forts in Europe map. But if that happen a lot in Global or Pacific map I agree that it looks like a problem with forts vs towns.I do wonder if the AI overvalues forts -- sure it is better than defending open ground, but unless it is a chokepoint it may not be wise. If forts had minor AA capability it might make it worthwhile to hole up there, though there would still come a time strategically when they would be better off defending their cities instead.