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.