The article link mentions how in the 1960's SEN was the 3rd largest airport in terms of passenger numbers. The current congestion at London airports mean that it is only a matter of time until SEN comes into its own. I believe it will take off in a big way. If you like convenience, it is a super little airport.
It does need to attract another airline who has a brand presence abroad in European markets and can sell a London route, like Wizz, Vueling, Transavia (FR/NL markets), and perhaps the likes of Air Arabia. Though there are reasons why some of these airlines dont fly there (Wizz scale at LTN for one), I do believe that with small improvement the dial will finally turn.
The current challenge I believe is that the services being provided rely too heavily on the local catchment (which Stobart puts at c.600k). The Flybe brand is virtually unknown in continental EU, and though easyJet is well known the lions share of its routes are to sun spots that will always be mostly suited or supported by a Southend/London/SE England audience. Those routes by easyJet which operate from big markets like AMS where Easyjet is well known do great.
EI-BUD