dc9-32...Its very easy to be highly critical and I'm no fan of many aspects of LTN's current infrastructure.
However, be realistic! The airport was originally developed to handle a tiny fraction of the current throughput in an age when flying was still very much a luxury and the package holiday industry was in its infancy. Its a very challenging site with several major issues including hangars and other infrastructure limiting development. Then there is the local topography! Comparing LTN to most other similar sized UK airports is hardly relevant as apart from what has already been mentioned, LTN also manages to squeeze in an ever growing number of exec jets which also produces many challenges.
Of course, I hope the planned development addresses many of the current issues but I'm also not expecting miracles!