Yasuo's Q - Why Is It Not Coded As AoE?
This "feature" is annoying as hell when paired with
on Yasuo.
Death's Dance includes a passive that heals for 15% of the damage done by abilities. According to its description, that healing should be reduced to 5% on AoE abilities. However, both Yasuo's normal Q--and his empowered tornado Q--heal for the full 15% on the first target they hit.
To answer my own question, it's probably because his Q is coded as an empowered auto which procs effects like Fleet Footwork, Grasp, etc., but this should seriously be looked into. Thankfully, not many people build this particular item over
... Though when they do, I definitely notice the difference, especially in team fights.

healing the full 15% on both hits of her Q (if they land). With Vel'koz, if I were to build Hextech Revolver, my Q would only heal for the AoE damage amount of 5% despite its first hit being a single target spell.