I’m not so sure about the southern thing but I do think that the GOP is far too focused on appealing to rural voters rather urban ones. When you look at the electoral map (zoom in to see counties) the more densely populated areas almost always go Dem. I know the tired old explanation about minorities and welfare/social programs but these areas also contain educated professionals, white collar workers, etc. These are people that feel increasingly alienated by rural social values and attitudes towards science.
I think that’s why Rudy had so little appeal. The attitude towards guns, gays and abortions in NYC is very different than in rural Mississippi. I have no doubt that Rudy was smart enough to know the difference but I don’t think voters could grasp the difference.