If I'm being honest I always preferred going assassin Yasuo with full crit. I feel as though it was a good playstyle for him, and very rewarding when pulled off. Plus, when you're squishy like that it's even better when you outplay your opponents with him. The early game is where Yasuo is at his weakest, so I'm not sure how much nerfing that would effect him. I'd have to see what it is exactly they're targeting, but I'm assuming they're hitting his base damage. Regardless, if you know your stuff, you can scale into late game, where Yasuo shines best, and make all your opponents you know... have their last breath.
Ahem.
As for tank items. All though I am not sure how good of an idea it is for the game, or viable I guess? I think as I said before if they limited certain tank items to actual tanks only it would help deal with this problem that seems to reoccur. I don't think nerfing tank items is the right way to go, but I do think limiting the champs that can get them would. In most cases, dare I say all, really. I don't think it's viable at all for adc's to build things like Randuin's, Sunfire, etc. Same goes for most mages and assassins. I think if they did something similar to how hydra is limited to melee champs it could work out. Granted, something like this would take a lot of thought considering the amount of champions and such, but it's safe to say that the champs that you want to go straight up damage with a GA and things like MS and Maw shouldn't even have the option to buy the more tanky items.