bounty, I think you will find that bmi stopped doing their double-stops so they could offer a direct GLA-CPH service, but more importantly a new twice daily EDI-CPH service offering the conections as well as a better business schedule. Prior to this bmi didn't offer a morning flight from EDI to CPH!
This was at the same time as them starting EDI-SYY and improving their EDI-MAN times for the USA connections from Manchester (IAD & ORD). They have sinced also commenced EDI-JER daily! This goes alongside their existing BRU, LBA & LHR services.
Obviously bmi saw the potential that EDI has to offer for a full-service airlines vs that of GLA where it only offers LHR, MAN, CPH & LBA! Oh and JER at weekend if that counts as a route!!
In another case, DUO decided to launch MXP, GVA, ZRH & OSL from EDI, not GLA, as they too saw the benefits EDI can bring from a business sense, but especailly for inbound tourism (I personally love Glasgow, one of my favourtie cities, but EDI certainly has more appeal overseas).
Certainly this side of things will make EDI also more attractive for longhaul flights. The one thing that GLA does have though is the population (although if there was a EDI-JFK service I'm sure people in GLA will drive to EDI), but, perhaps and more importantly, the airport services.