Rules change
The A340 was designed for the "long thin" routes of the time, when the ETOPS rules were diffent from now, while the A330 was for the "shorter and thicker" legs (Freud, where art thou?) and by skilful engineering Airbus was able to cover the different needs with, basically, one airframe.
A lot of statistical analyses were brought to bear on the FAA to prove that the 777 was able to cover the "long, thin and lonely" routes, whether overland or water, so the rules under which the A340 had the advantage were changed and in the Airbus line-up, the A330 was able to fulfil the role and '340 orders dried up - Darwin rules OK ...
Nothing in the above should be read as even hinting that the A340 was a "wrong" choice - it was "right" for its time - nor that there was any skulduggery in "Brand X" getting the rules changed. The rules were uinder constant surveillance since the time when the original A300 was allowed to fly services from e.g. Miami to the Caribbean, "way back when".