You mean reducing his crit damage by 10%? That doesn't really compensate for anything.
Let's do a little math here:
An ADC with an IE and a Shiv will have 50% crit chance and deal 200% of his AD per crit.
Yasuo with the same build will have a 100% crit chance and deal 180% of his AD.
Let's say both of them have 100 AD for the sake of having a nice, round number.
Over 10 attacks, on average, 5 of them will crit for the ADC. That's 1500 damage total.
Now, we look at Yasuo: Over the same 10 attacks, Yasuo will crit every single time for 180 damage each. That's 1800 damage. That's 20% more damage from just auto attacks.
This doesn't seem like much, the the issue is that an ADC will have to build a second zeal item to get equivalent damage output with the same AD. This means that Yasuo can scale into his hypercarry status far faster than an ADC with equivalent gold.
But now to the meat of it. League of Legends does not exist in a vacuum, so if we assume that an ADC's 4th item will give them 80% crit, we have to factor in what Yasuo's 4th item might be. Since Yasuo only needs 2 items to have 100% crit unlike ADC's who need 4 items for it, this leaves 3 slots if he keeps boots for pure AD items like Bloodthirster, Youmuu's and a Duskblade, upwards of 75 AD more in the late game.
This doesn't include the % bonus armor pen from his ult, nor does it factor in the armor pen from his items, but once you factor those in, Yasuo can deal superior DPS by just right clicking than an ADC can at full build and auto attacks are only a portion of his total damage output. His Q has a 100% AD ratio. His ult has a 150% AD ratio. These two alone are far more than most carries have over all of their abilities.
And I'm talking about late late game where everyone is full build. We're not even mentioning the mid game where Yasuo is already popping off and going super hard while most carries are still ramping up.
TL;DR: These free stats mean more consistent games because Yasuo can start hypercarrying from earlier in the game and inevitably scale harder into the late game. His shield can soak up 1-2 autos from another fed carry, which basically means that they start the fight losing if he ends up dueling them. Mix in his CC and gap closing and there's little reason to see why people hate Yasuo so much.
I love his kit, it's really nice that requires at least some experience to play decently but there's no denying that once someone plays 20 or so games with him that they begin to understand how he plays, what his weakness' are and how to best exploit other people's weakness'. He's punished less from trading with his shield and his scaling rewards him even more.
