Whats the fixation on here with 737-800, other versions area available and are used,500/600 etc and there are A318 operators in Europe, not to mention FlyBE and the Dash 8 from IOM-MAH etc.
No I think previous posters have hit the nail on the head, the real reason I would suggest is that operators just dont want to expand into europe not that they dont have the right runway or a/c type.
If we take a less BHD/BFS focused look at it, Ireland as an Island nation can at best probably sustain a select few route that will be profitable from both DUB and BHD/BFS, but i would suggest that very very few would sustain operations from DUB/BFS or DUB/BHD, in deed as has been shown in ROI, CZECH and Malev both pulled the ORK routes as they said they could not make ORK and DUB work.
Air Baltic fro example to RIX and VNO from Belfast maintain nearly 30% of there pax are from the North.
I think in the short term we just have to support what routes and operators we have and just let others huff and puff and realise that they cant get what they want all the time. Maybe daddy might take them too Runways r Us and buy him a new runway to play with.