Legendary Akali Skins

Today was one of those days where you log in and get bombarded with notifications. After dismissing them I see a dot on my collection directing me to the skins tab. When scrolling through I ran into my Akali skins. As an Akali main I hadn't given it much thought, but why is there no legendary skin for her. All there is are a couple of legacy and a single epic skin. Why aren't there any skins for her if Tristana, Cho'Gath, and Corki all have two?