That action in itself has some legitimate technical reasons at least - fighter jets are very envelope pushing and often cannot land safely while carrying a sufficiently full load of fuel. Say the jet can only land safely at 35% or less fuel capacity, is at 50% and needs to reach a target which requires at least 70% capacity to reach, fight, and return. Midair refueling isn't an option for whatever reason and others are logistically committed. Dumping 15% and landing to refuel before launching could make sense.
Granted stupid waste without any valid tactical or strategic edge case reasons aren't exactly unheard of in the military either.
Granted stupid waste without any valid tactical or strategic edge case reasons aren't exactly unheard of in the military either.