As for NOC, why not have a transatlantic flight? Any time I've been holidaying in Connaught, the place has been full of Americans, so I'd reckon, anecdotally, that there'd be plenty of inbound passengers.
There's Americans all over Ireland, it doesn't mean every airport in the country should have it's own route to the states. It comes down to economies of scale, the West coast would be better served with multiple daily flights through Shannon than multiple weekly flights spread throughout airports along the West coast.