Could it be a good idea to just return the Attack Speed Debuff to Lee's kit and remove the slow?
I mean, realistically, that's his only CC pre-6 and it's pretty overwhelming if he gets early points in it. And the removal of the Attack Speed Debuff a) only effects Auto-Attack reliant champions AND b) pretty much inadvertently killed (or at least maimed) 'Lane Sin' because it was a huge chunk of his trading potential both in lane and when trying to assassinate someone in the mid game.
He used to counter Olaf, Zed, Fiora - even Irelia to a degree. Now he just gets chunked if he tries to trade. I mean, sure. he can still 100-0% someone if he gets a couple of early kills but it rarely happens nowadays.
I would be happy with Riot if they did something like this because they really hurt his capacity to lane when they went after bland, no-damage, CC bot Lee Sin Jungle the the Esports scene is so fixated with.
Hell, Riot. Why does Lee's E even deal Magic damage? That just screams "it's strong early so we'll just gimp the ability's late game."