Kai'Sa was a failure
Clickbaited - or not.
She was a huge success in many ways in my opinion, but I can never say she's a "highly-mechanical" champion. Her mechanics only require a basic level of MOBA/League knowledge to play. (53% winrate and 13% pickrate do indicate her lack of mechanics for someone Riot claimed to be difficult)
Riot stated they're basing her off Vayne but Vayne, funnily, actually takes more skill to shred teams/tanks. Kai'Sa has the benefit of multi-target damage and late-game exceeds Vayne by a mile simply because her passive is magic damage while her autoattacks are physical. Basically, she will shred you no matter what. Even though Vayne does the same, at least it's not multi-target. TL;DR - She's too easy.
Now - don't misinterpret me and look at this as a complaint on Kai'Sa. Her gameplay is fine to me. However, I believe Vayne takes so much more skill to play effectively than Kai'Sa while Kai'Sa is wait and farm. I was disappointed on how mechanically intensive her kit was because high mechanics requires abilities that can be used quickly and efficiently.
I would compare Kai'Sa to old Jinx with Vayne's burst. Even the new Irelia is more mechanically intensive than Kai'Sa in my opinion.
I hope next time I see a highly-mechanical champion in the works, Riot stays true to it.
Suggestions? Well, not much since her kit is already completed so I can't make it mechanically intensive but here's what I would do while trying to keep her mechanically intensive.
Note: AGAIN, THESE ARE SUGGESTIONS. NOT TESTED and I feel her champion is already complete so. This is if she was still being developed.
Revert range to 500 (no compensation buffs) Keep AP ratio buffs Decrease E CD to 12/10/8/6/5 and AS steroid to 20/25/30/40/50% for 5 to 2 seconds
Makes her reliant on always risking being right next to the enemy but mechanically intensive with her E to constantly reposition. (No point in low mana costs when her E doesn't go off as frequently even late-game compared to Vayne) AP ratios help execute and keep her on equal teams with other ADC damage and as an assassin, her R let's her access and shred the backline.