Manchester remains the dominant airport within the north of England...period. MAN will always be the place for longhaul traffic from the north of England, the fact that short haul from other fields has developed should be welcomed.
To lament the fact that other airfields have developed, at the expense of MAN, over the recent past, is a particularly Mancunian outlook. People that reside outside Greater Manchester would argue that more fllights from LPL and LBA, for example, were a long time coming. Yes Manchester has surface transport links that are superior, particularly compared to LBA...however travellers from the Leeds and Bradford conurbations are still likely to find LBA an easier option than MAN. As a former resident of a BD postcode, the thought of trekking the M62 to MAN, especially in winter, is enough to fill one with dread with regard to making one's flight in a timely fashion.
For years MAN benefited from the North of Engalnd public having almost no choice than to fly from Ringway on IT flights (the based units at MAN outnumbered the collective units at LPL, EMA, HUY, LBA, MME and NCL by a significant factor..and it still does today, albeit reduced). However, the market changed and IT opertions fell out of favour against loco scheduled, MAN thought they were above that market and in the end they suffered. The fact that these locos have erroded some routes outside the core bucket and spade routes offered by loco is just one of those things!
To say that LBA and LPL can complement MAN is fine but to duplicate is wrong....I disagree. Yes MAN ought to be serving the Far East and the US West Coast....MAN has the specific infrastrucure to handle such flights, but to say that LPL/LBA etc shouldn't also handle flights to European hubs, or holiday locations would relegate them to a route network that would not be able to support their ongoing operation. This is not a opinion that people to the east of the Pennines, at least, would not support.