Thank you for sharing your opinion as a Kat main, you are definitely correct in what you are saying; for the most part.
That said, she feels almost identical in teamfights given her mass AOE (especially after first reset).
While her damage isn't instant, it's pretty much instant the moment her first dagger lands, as that's all she needs to start her multikill.
Her laning is also still rather crappy, she's just a little better, just a lot less safe.
Honestly its probably one of the best reworks riot has done to a champion.
Sort of...I'm still extremely skeptical about every rework that came from the Assassin Class Update, which just felt unnecessary. She's definitely one of Riot's better reworks, and yet, she still feels like a balance nightmare. Like, when I get fed I know it's because I am better than my opponents (my friends drag the elo down dramatically), however, there is an element of me knowing that I could never demolish this hard on any of the other champions I play...and I don't know whether that's because of me or my champion. With pre-rework Kat I knew it was me carrying a terrible champ, but with this Kat I never know.
I do think she's a lot easier to counterplay at low-mid levels of play, however at higher levels of play where Kat one tricks actually possess brains I feel like she's an extremely unhealthy champion that is impossible to balance.
She's essentially just an AP Riven at this point, minus the CC and shield.
tl;dr She's healthier in a lot of areas but a nightmare in others