In short, Airbus designed the A330/340 because at the time it was the only way to provide a family of 300-seat airplanes capable of flying 1,000-7,000nm ranges. The A330/340 go back to the days of the TA 9 (twin) and TA 11 (quad) airplanes, which were substantial developments of the A300. It was only in the mid-1980s that Airbus decided to make the two new types common types. Very late in pre-development the A340-300 and A330-300 fuselages actually became the same length, whereas the A330 had usually been a few frames shorter.
Some suggest that it was too much for Airbus designers to break with the tradition of the TA 9 and TA 11 blue prints. Besides, the consortium did its homework and found that at a range of about 5,500nm a quad DID become cheaper to operate than a twin. However, Airbus based this ascertation on the bypass and pressure ratios of a jet turbine comparable to that of those found on the Boeing 767. However, Boeing also did their homework, and found that the new larger engines for the 777 could have much higher bypass and pressure ratios, meaning increased efficiencies, and basically Airbus' old 5,500nm report is now irrelevant.
Also, in 1987 when the A330/340 was launched the big engine manufacturers weren't technologically ready for a massive leap in engine power. Actually, development of A330 engines helped Boeing convince them to go "the big one" and develop 777 powerplants. Don't forget that the 777 was launched more that 3 years after the A330/340.
Having spoken to several engineers involved with the A330/340 project, each has admitted that if they could have designed a twin A340, they would have. But I stress here that this does not make the A340 an inefficient airplane. It is a 747-400 killer - so is the 777-200ER.
With regards to ETOPS, Airbus is not against 207 minutes ETOPS, but is against ad hoc ETOPS planning. Boeing agrees - the ETOPS regulation - FAA AC 120-42A - is outdated and need to be upgraded. Of course, Airbus has an advantage in delaying 207 minutes ETOPS as long as possible and good luck to them. It is not an unfair tactic, and if we have safer regulations as a result I say bring it on! Airbus is very clever in that they have not said the ETOPS is unreliable. The A340-500/600 are being designed and constructed to ETOPS standards.
I might add, too, that when we are talking about multi-billion dollar widebody airplane deals, why wouldn't you try to give yourself an advantage? It's as American as capitalism.