"What was Airbuses thinking behind bringing out a 4 engined jet in this market?"
Basically, as I said, they could produce a new medium range airliner, the A330, and a long range airliner, the A340, simultaneously and with about 90% commonality between the two - hence greatly reducing the development costs of both types.
"Okay, but what is in it for the airline in terms of selling points ?"
What about Virgin's "4 engines for long haul" slogan. Don't know if it had much impact on their pax but they thought it was a selling point.