This game is weird. Kitana is solid, but not top tier. This game is mix up heavy and Kitana does not have them. What she does have however are easy converts into a lot of meterless damage. I say there is some balance. I think if her overhead was slightly faster she'd be able to romp with the higher tier people just fine because now people would have to respect the word defense. It's not about being a "smarter fighter." It's about balance.
A lot of people hate on mournful but it can help you open people up more and it's a little safer. Remember this game is about opening people up more than damage. One bar of mournful does create setups and lead to good damage. Think of it as Kung Lao needs bar for ex hat spin.
She also has air mobility in a game where everyone has the same jump arc.
By the way Mileena suffers more than Kitana at opening people up. They are essentially the same, Kitana has easier and safer confirms into more damage. I love Mileena more than any character, but now I'm using more Kitana because she is way less YOLO. Please don't argue about Mileena's f3 opener because it's 32 frames. And Mileena's MB Ethereal stance moves literally do nothing.
Another way they can balance the game is changing frame data, walk speed, and gravity / juggling per variation.