My guess is that Kiara doesn't care about being overly feminine. I mean, cub Nala from the first movie was somewhat feminine in design, a few of her mannerisms but well...she was adventurous, she wasn't easily offended by gross things, also as an adult she fights on the front lines with 0 complaints.
I dont have much in the way of tlk headcanon but the way I see it, Kiara and Nala know they are pretty kitties. No need to flaunt it. They know they have feminine beauty, no need for them to obsess over it.
Tiifu and zuri seem...a lot less confident in themselves.