The problem is that the airfield (not "airport", airfield, there is a difference) is run by the council. Councils generally are not good at all at running very many things. And they certainly wouldn't know how to operate an aerodrome properly.
Were it handed over to another operator with half a scooby doo about how to run an airfield business would probably pick up substantially.
Petty arguments, the millstones of politics & local government and zealousness with regards to enforcing operating procedures (MORs etc.) have damaged Oban's reputation, which also damages business.
There is also the sad fact of political egoism - shared among many airfield operators - that the operator (A&B Council) cannot accept that Oban is not an Intergalactic Spaceport, it never will be and it is "merely" a small General Aviation airfield (and a damn fine one at that) and that its clientelle will never move beyond private singles/twins and the occassional smallest of exec turboprops/jets (with the odd commercial inter-island light twin every now and then). If the operators understood and accepted that and focussed on attracting business from this group instead of trying to mould it into some sort of mini-Heathrow then things would look very bright indeed for Oban.
Smithy