Why does Kayn need the ability to walk through walls?

Just played a ranked vs Kayn and it was so annoying how he can just walk through a wall when a fight doesnt go his way. I dont understand why a mechanic like that needs to be put in the game. At least with Talon you know he will go over in the direction he jumped and with Bard you can follow him. But Kayn can just wait to see what you're going to do first. As a volibear main this season it makes me sad the voli is pushed even farther down the tier list. When every new champion has a dash/self peel or built in wall hax. Like shouldn't we choose champions who have the ability to peel our carries? shouldn't champions have trade offs? instead of every carry/top/jung/mid having their own personal root/dash/wallhax.

I personally think abilities like Shadowstep and Assassins path are just high reward low risk abilities that aren't healthy for the game. I also don't understand why these abilities need to be on high damage assassins. It doesnt even matter if they are out of position, they have a get out of jail free card. Maybe instead of these abilities riot should just give them a dash or a charge system on those abilities.

Imo, it just isnt fun to play against when your only solution to follow up is flash. Rant over you can flame me now.