Maybe they wanted the plane to go slower (Airbus A340 travels only Mach 0.78-0.80)
jk (just kidding)
Well maybe they assumed that would handle their expectations for the time being, Cathay Pacific has some wonderful looking Boeing 747's (i think no other 747 could look better) and it's possible that they are doing what you lead up to CX747. A340 also has a longer range, depending on the seat configuration.
johans | firstname.lastname@example.org
Petlaluma, CA USA
"And God commanded the chicken to cross the road,
and the chicken crossed the road, and there was
much rejoicing." -Moses