ALL airports around the world lose air service, hugely disappointing as it is, it's not a purely MAN phenomenon. London no longer has
PR or GA, and it's impossible to fly direct to Durban, Lilongwe, Santiago, San Diego, Brisbane, Adelaide etc. Melbourne lost BA, Brussels lost its hub status and Far East airlines, Chicago has lost plenty too.
What Manchester has always suffered from is an overly ambitious management, promises to be a 'Gateway to the World', but unfortunately a relative lack of high yielding business passengers, when compared to other cities. It's obscene still that the vast bulk of big British business/corporations have become based in the south east, but although that's not a topic for this forum, it goes a long way in explaining air service provision.
From the rather sad list you give Mr A Tis, there is still plenty of demand for the cities these airlines served, but in general there was a greater need for these airlines to consolidate operations, and maximise slot availability at London. One or two of them said this was the case, MK for example. Oh, and NW has never served MAN with passenger flights!
The best way to look at it I find, is to remind yourself that for a non-capital city airport, and for a non-hub, having so many successful transatlantic services and the daily SQ service is still pretty good going.
I think that T2 initially was planned as an intercontinental terminal, like LHR3 and it would have been with BW QF MH CX SA and AI at the stands.