To be honest LTNs ambitions are seriously limited by the length of runway when it comes to long haul.
They probably see the likes of Silverjet and LaCompagnie as the only feasible options of getting scheduled links to the likes of the US, Dubai etc.
If an American full service Airline was interested in LTN I am sure an Airbridge would be an incentive but as most have said other than that or EL AL why would the Airport invest.
Guess the question is did EL AL even use an Airbridge at STN when they were there?
LTN is simply a low cost Airport.
Don't suppose the recent boundary changes being made by the Government will have any effect on the Airport?