Stepney, that rant was almost Daily Mail esque! I ticked off the bingo card at least six old favourites....
My dear Doktorb, the fact that it is "almost Daily Mail esque", as George Orwell almost said, doesn't mean it's wrong. My own opinions on Welsh were expressed on another place a while back. The only arguments against seemed to be sentimentality; a misguided belief that other, divisive, cultures should be fostered and nurtured; and Welsh nationalism.
If you would like to dispute that the lingua franca of Wales south of, say, Aberystwyth and Montgomery, is English, and that most people south of that line barely speak Welsh, I'd like to hear the argument. If it's that we should artificially foster such a half-dead tongue as Welsh through the nomenclature of seats in the House of Commons, there is a case against it that is almost unanswerable.
Linguistic diversity, like many if not most types of diversity, is an intrinsic and positive good.