EDI is the Heathrow of the North (wait for it) in that BAA (as was) just added bits on willy nilly with no strategic vision. It was all about as little capital investment as possible with the medium term result of having a layout no sane person would ever have proposed from day one. The layout at GLA was much more open to growth, every time I fly through EDI I just wish they'd build a whole new airport at Ingleston and knock them old one down. As I have said before, the South East Pier should have been phase one of a whole new bespoke terminal instead of a tacked on metal pier.
There are drawbacks to having no taxpayer stake in such strategic infrastructure as private sector only ownership is wholly profit driven and focussed wholly short to medium term planning with no long term view.