Most airliners are low-wing, meaning that positioning of the bomb bay(s) becomes a tricky engineering thing, particularly with center of gravity. Witness the various positioning of the 737-derived P-8s weapons bay from front to aft (due in large part to allow mounting of an external side scan radar) prior to design freeze.
Have you considered the role dihedral plays?
Wings that slope downward from the fuselage tend to enhance maneuverability (crucial for military aircraft), whereas wings that slope upward from the fuselage enhance stability (good for passenger comfort).
A downward sloping wing, positioned low on the fuselage, would risk encountering far too much ground contact. That’s the main reason why military aircraft tend to be high-wing.