What's the point of Aatrox?

Aatrox doesn't have any unique skills. He's bunch of already existing very popular abilities (dash, knock up, 3rd auto, skillshot slow, AoE damage, AS speed buff, revivie).
His gameplay and balance are very binary. He either lifesteals enough to outduel the other top laners and he's unstoppable duelist. Or he doesn't lifesteal enough and he's useless. There isn't any outplaying or being outplayed as Aatrox. Just stats vs stats.

His visual and voice design are boring. Hurr durr, I'm a very dark and mysterious demon.
His lore started something (1 of few "Darkins" from ancient conflict, if I remember correctly) and.... Riot just left it there and never continued.

Today, he's left in underpowered state. With lore, that doesn't lead to anything. Weak and forgotten. To make him good and interesting champion, Riot would probably have to COMPLETELY change everything about him. But in that case, they might as well make new champion.
I'm just wondering, why does something like Aatrox even exist in this game.