Hi
Grity,
ok, it is not realy significant with pitch 15 deg, but also for the calculation for the pich-up moment for the engins (toga...) you need the different in height between the engins and CG...
In the context of calculations of moments relative to the CG, the longitudinal components of aero forces and the "vertical" distance (i.e. the distance measured along the yaw axis) between the CG and the wing mean chord are both low and the resulting moment is generally negligible. In any case, the moment coefficients depend mainly on AoA, not on attitude.
You are right about the moments due to engine thrust.