Upon my honour I do swear undying loyalty to the Emperor, Titus Mede II, and unwavering obedience to the officers of his great Empire. May those above judge me, and those below take me, if I fail in my duty. Long live the Emperor! Long live the Empire!
That’s the point. In Oblivion, like half of the people remembered Tiber Septim, and even Martin was talked by everyone who knew of him. Titus Mede is never talked, like “Emperor? Wait, whathisname, no matter”, it’s just empire this empire that. He could disappear and Penitus Oculatus maybe would notice. He gets talked around the quest to assassinate him. Hell, nothing happens at all after you kill him too.