Cost, choice and frequency of flights is what its all about. Iam sure BA, bmi, flybe etc etc would welcome with open arms 1 single airport. All the airlines could streamline their operations and offer better and more efficient services.
FACT, Simple economies of scale...
One could make the same argument about London City and Heathrow being combined except City serves the local business population. Having to go twice as far from both Edinburgh and Glasgow to this airport than we do right now is remniscent of 1970s central planning. The people of Glasgow have an airport, as do the people of Edinburgh. I frequently use both and they work quite well. Grandiose schemes of a hub airport in the middle of nowehere with amazing transport links to everywhere.......? I mean come on. Have you ever visited the UK after 10 years of the Nanny Party in power?