Maybe it all comes down to the decision back in the 60's to build the terminal away from the station. Both the airport and the railway would have served each other with passengers if there had been a Southend type connection?
The question has to be asked why the gradual decline over many decades if it isn't down to a lack of investment and poor judgments?
The airport reminds me of my local pub, 20 odd years ago it was always busy. It changed hands a couple of times and now it has lost its way. It is now looking rough at the edges and needs an upgrade but no money has been spent on it for years. The opening times reduced and it is often now closed when it is meant to be open. The car park is usually empty and now hardly anyone goes there. I bit like this airport I guess.