If you've been in a game as, with, or against the newest League of Legends
After taking in all of his flashy wall-walking abilities and discerning his best build paths, players were able to pick up on his lack of outlining pretty quickly. It certainly sets him apart from other champs since he's the first to have his change, and while plenty of players welcomed the change, after over 100 champions of consistency, some were a bit resistant to the idea.
It's no wonder then that the question about Kayn's lack of inking was one of the first
"The current implementation of inking is performance intensive for what it does so we're exploring the possibility of phasing inking out in favor of a better solution," the Rioter answered when asked what the deal was with the inking. "We wanted to ship Kayn without inking to get player feedback and get a sense of how noticeable its absence was. The reason we chose Kayn to test this is that the Assassin form's hair uses transparency, which is something that inking interferes with (which is another downside of the tech)."
Another Rioter provided an additional response further down that explained some of the options that were being explored with inking, specifically when it came to Kayn. Below is a picture of three options that they looked at where you can better see the difference between the models.
As the first Rioter said, inking can sometimes impact the game's performance on some computers, a factor that warrants the option that's already in place in the game's settings to turn off inking. There's no verdict on the inking decision yet, but they're taking into account everyone's feedback on how Kayn looks.