Strike missions after "air superiority" been achieved or some may just be designated to carry external loads while others are "hidden" to cover them. It also makes sense to eventually stream line to fewer aircraft models than to try to maintain 10-20 types.
What's the point of all the external hard points after putting all the effort to give it internal hardpoints and stealth shaping? If they want it to carry heavy antiship missiles, then the internals should be designed for that scenario.