No, it's because the engineers have to balance structure weight versus everything else. F-15As are G limited to 7.3G. The Cs are limited to that same amount at

No, it's because the engineers have to balance structure weight versus everything else. F-15As are G limited to 7.3G. The Cs are limited to that same amount at altitude. F-18s were limited to 7.5G as well. And both of those are with "clean" aircraft. Start putting munitions and external fuel on, and that limit starts going down, because they wings have more weight to withstand.