OK...Size is of course nice, I'd be lying if I said otherwise. Although, I have noticed men who aren't as big definately make up the difference in other areas (if you know what I mean)
Sex is about the entire experience. I too could take care of myself if all I wanted was to "get off". Its like going out to eat vs staying home and cooking. You go out for the ambiance, being waited on and pampered, feeling special. By the way, I very rarely go to McDonalds! I am much more into quality dining than quick service!!!!!