The irony is that there is way too little runway capacity in the SE and far too much elsewhere in the regions. Much of the latter was originally developed for military use, and is now redundant; indeed just how many of our remaining military air bases do we really need?
There is runway capacity but desire is to grow airports bigger so flights can be offered to far flung destinations using transit passengers who add nothing, spend nothing.
Too many vested interests and nimbys to change the policy.