I know what you mean about 'english' harmonies. From the viewpoint of being english, I listen to american stuff and notice that the harmonies that tend to be prevelant (well at least in the stuff I've heard) are noticeably different to those used over here.

I think it has to do with accents. How you speak a sentence and how you sing it are not so different unless you have a different accent and working vocabulary. I reckon that people pick up on the sounds they're used to. Also the 'english' harmonies are more straightforward. Or, if you like, less subtle..... :0)