For a V/STOL aircraft like the Harrier gyroscopic precession is important as it adversely affects hovering stability. That's why the Pegasus engine has counter-rotating shafts. Counter rotating shafts in engines like the RR
Trent are more for aerodynamic reasons than to reduce precession torque. Airliners don't usually pitch or yaw at high rates so any precession torque will be relatively low, but it is taken into account when stressing the engine mountings. It's more likely to be significant in a military fighter as a rapid pitch up will create a yawing moment.
The glass isn't half empty, or half full, it's twice as big as it needs to be.