They also, for example, provide adequate seating in the departure lounge whereas SEN's competitors are obsessed with herding people into shopping malls and keeping them there until the last possible moment. It seems that the latter model isn't what most travellers want to experience.
I would think Southend would love more retail units and their kindness has nothing to do with providing the maximum number of seats possible but the fact that shops need plenty of passengers. As Southend grows its passenger base the seats will be replaced with retail.