Ahh - but, dear ORAC, your LM proposal is merely single-role. A total waste of an airframe when you don't need war numbers of tankers. Whereas GTTA is multi-role - so when it isn't needed as a tanker it can still work as a passenger and/or cargo aircraft. Or it can do a bit of all 3 roles concurrently. Except that, without any windows, it'll be pretty bŁoody awful to fly in as a passenger!