The fear can interrupt things. He's also got a stealth, and his ult can be used to disintegrate entire ults. I've seen't it, dawg.
Master Yi literally has Q and attack speed. Nerfing the self heal will only punish good Yis for being good and make bad Yis worse; nerfing his damage will remove his use and basically obsolete him. You might as well then pick a juggernaut because at least you'll live longer. Vi is probably a suitable replacement. If he can't beeline to or away from something, he doesn't do much. Shaco at least has something going on in his kit where yes, he needs damage but he can still contribute without.
Yi isn't bad, he's just a one-trick-pony by design, which can make him very easy to counter. He's also generally mulch in a teamfight as soon as the enemy tank shows up.
Now, Caitlyn? She could use looking at.
Riven I don't really know enough about competitively to comment on. People say she has to 'animation cancel,' and that sounds like the dude who quit his Smash Bros tourney because his controller wasn't defective enough to let him glitch past the game's natural controls. It's broken, but because some babbys don't want to relearn a (literally) broken champion, Riot won't push her to a direction where she doesn't need to be broken.
I'm not sure why people downvoted my first comment. I was asking how they want to nerf Yi...