Yasuo is far more balanceable than Kalista or Azir, true. But it isn't just his itemization or the meta that makes him obnoxious cancer to play against. He has a lot of extraneous power he doesn't need to function. Presently, he also has almost no windows of vulnerability and when trying to engage with him it feels like you have to ask his permission for everything.
There's no reason he needs to sit on his Q3 so long during the laning phase. It should be far shorter, probably around 6 seconds.
There's no reason why Yasuo's Windwall needs to last so long at early ranks. During late game teamfights it is mostly a zoning tool, and that's fine. But the fact that he can E through minions and onto you, auto you, Q you, and put up a Windwall and run in and out of it should you attempt an all-in, or otherwise just cover his escape flawlessly with it, is frustrating. Not to mention the Yasuo players who deny you farm or the ability to waveclear with it. It might not happen more than a couple of times in a game, and in far from every game, but it's extremely irritating to have a Yasuo push up to your tower and then deny you the few minions you could have last hit if it weren't for Windwall, especially when, in theory, his reckless use of the ability should mean he is prey, but he's Yasuo so that isn't true.
There's also no reason that the Windwall hitbox needs to start inside of his, because it's very frustrating to have a projectile on top of him get Windwall'd at the last possible second. He should really have to exercise a bit more finesse about using it.
There's no reason Yasuo's E needs its CD to be down to .1 seconds. It should really go no lower than .2, so that you have a tad bit more time to react to him when he trades with you in the lane. It sounds like no big deal, but it ends up being quite significant.
There's no reason Yasuo's R needs to grant him bonus armor penetration against every target. It should be an armor reduction on the target(s) he hits, instead, and for a more reasonable duration.
There's no reason Yasuo's R needs to still be castable if you QSS out of a knockup.
There's no reason Yasuo's R needs to place him outside of turret range if possible.