It's called continual improvement except this is the first building work to the passenger infrastructure for a few years so I don't know what you are talking about when you say a building site since the 1980's.
In the 1980's the airport had a capacity of 3.5 million, in a few short years it will be 18 million which is some 5 times bigger.
I think you will find there has been a lot of building work carried out at other UK airport so maybe your same analogy could be used at these airports as well.
(Edit) I have just gone back over my photo collection as I like to record infrastructure changes. The last change to the inside of the terminal was 10 years ago in 2004 when the departure lounge was opened and the pier was built. In 2003 the North Apron was built Since then it has just been tinkering with the drop off area's and the exit road, all of which was rather minor.
Last edited by LTNman; 28th Aug 2014 at 19:07.