I really don't think that you can call the Flybe/Stobart Air route network "small airport to small airport" as the "particular connection" is this case is metropolitan London.
One can reasonably argue the merits of the various London airports with regard to their travel times to different parts of London, but I'm sure that potential travellers from the European cities on the network will consider London Southend a perfectly acceptable arrival airport.
Effective marketing is usually the key to success in the case of routes which have previously been unserved for a period of time and I'm sure the parties concerned are trying very hard to achieve that in this case.