Reply #4: The idea is national representation

[liberalpragmatist]

I'm not British btw, but it has to do with the idea that each representative is representing a slice of the country as a whole, not his or her district (although they do try to be good to their districts since they want to be reelected).

India does the same thing. And it was this that the British used to justify not giving the Americans representation in parliament before the American Revolution - the idea was that all the representatives in the House of Commons collectively represented the entire British realm.