There is no sexuality or actual 'p0rn' as the focusunless it is a doujinshi or hentai fan svc. storyline. The visually riveting & gratuitous element is the visceral & bloody nature of such combat and the war-romance of glamorized, high tech machines destroying each other; as visually addictive to tech-nerds as actual sexual content eg:
Massive exchanges of ordnance and stunning dogfight/combat maneuvers against cityscapes, alien environments or amidst massed fleets of capital ships and blossoming,null-'G'explosions; detailed, 'motion-physics' accurate and almost photo-realistic depictions of soldiers/pilots decompressing in hard vacuum, being eviscerated or burned alive; depictions of ordnance impacts and nuclear explosions, incl. progressive flash/blast/heat, that have otherwise only been captured with motion picture cameras using strobes, frame progression and other photography tricks.
Can apply to non-Japanese, SF motion pictures replete w/the aforementioned.