LTNman
I agree entirely with your point about the importance of an airport showcasing its successful routes in order to attract new operators, which makes the apparent decision to abandon DUB-SEN to the whim of Flybe all the more puzzling.
Surely to have maintained an Aer Lingus Regional presence and its transatlantic through booking facility would have been just such a success story. Whether or not it was making much contribution to profits would be a secondary consideration set against its marketing value to SEN's business development department. For an airport owner working hard to press its credentials, and which also owns an airline operating a fairly high profile route, to abandon that route seems an odd decision.
Any UK airport attending Routes this year would surely wish to have included a DUB route and its transatlantic connections within its CV.