wb999,
You are quite incorrect regarding your summarisation of, supposedly, how the likes NCL, LPL and LBA were 15 years ago, you might have only visited such airports for a package deal to the sun but others visited them for other purposes.
Not just 15 years ago, I can cast my mind back 25 or more years, in those days such airlines as BA, BMA, BCal, AirUK, Dan Air, Loganair aswell as all the smaller airlines that came and went, had quite a domestic route network.
One example, if I can recall AirUK's routes, from NCL AirUK offered routes to EDI, ABZ, STN and/or NWI aswell as, internationally, AMS and CPH, besides these NCL also had services to both LGW & LHR, no doubt Dan Air were offering services to Ireland pn the "Budgie" network and so on.
LBA, AirUK offered routes to STN, EDI, ABZ, BFS, AMS & CPH, BMA offered a LHR service whilst other operators offered other routes.
15 or more years ago LPL would have been the last airport I would have thought of for a package holiday, in those days LPL was only good for such routes as Ireland and IOM unless one wants to go even further back to BMA's LHR route and the days of Cambrian Airways!
Perhaps one of the lesser (slower) airports to develop was HUY, perhaps, because it's not anywhere in particular, even the name itself suggests it is beside a river rather than in or near a city and without a significant catchment area.
And, not so far down the road, there is Finningley, again without a significant catchment area, take a look how long it has taken HUY to get to where it is today, something like 40 years, well expect it to take Finningley a further 30+ years to get to a level that HUY is at today!