Kennen Should be Melee
I know this sounds absurd. but it would generally fit his kit waaaayyyy better if he was melee.
Reasons why?
for champs that are meant to all-in, it isnt beneficial to have moderately high cooldowns, no real gap closers, and then apc low base attack dmg for aa's. his kit seems cool but isnt viable because it is heavily item dependant, and WHEN itemizing, his kit suggests go tank so as to not eat a bunch of dmg for free when kited.
BUT, if you do that when ever you land a solid combo, you generally will not have enough dmg to execute your opponent.
vice versa, you get easily blown up for trying to get a combo off.
This said, the obvious choices to fix it are flat out buffs to damage and cooldowns. Riot doesnt want to do this for whatever reason. cool.
Hence why I propose make our ninja yordle melee. With this, Kennen:
Can gain mr per level (higher base stats in general). His Q can do slightly more damage, a lower cooldown, AND/OR gain slight cc (which is not so bad on a skillshot minions can eat). He can gain an increase on attack damage per lvl AND/OR lower the passive W proc to 4,3,2 aa's (depending on what feels balanced or make it lower with more points in W). His E can allow AA's, gain more movespeed, AND/OR have a generally lower cooldown as well. R can stay the same.
Like this, his flaw of losing to mobility/range stays relevant (if not more), but he becomes an all round better all in AP champion. Granted Kennen ADC would become a memory.
I'm not being random with this; this comes from lots of meh Kennen experiences, and I honestly feel it would make his kit more cohesive overall.
Thoughts?
EDIT:
Thematically, I realize Ninja Rat attacking with his regular AA as melee is laughable. It would be awesome to give him an electrically charged katana (and a later Sasuke skin), but Yasuo is essentially that.
I propose letting Kennen keep the shuriken, but make it one of those large Shuriken (Fuma Shuriken/Demon Shuriken?) or even a Ring Blade.
Now, More thoughts?