Kindred could still be called, thought of and / or considered male.
Only thing feminine about Kindred's physical body are her curves, but monsters can have those whether they be male or female.
Give Kindred a male voice and the vast majority if not all will call her male.
Anivia does count and champions are not as sexualized as you think splash art wise besides a select few, nothing wrong with a bit of skin showing since it is like that for women in real life as well and some like
would be partially be exempt because of lore
Plenty of fully clothed, no skin women such as
as well
- A small, but good amount of the non human male champs you see could have been female with no change in their splash whatsoever

Yes you could say that they look blatantly male, but looking at Rek'sai, Anivia, and even Kindred you can say the same, but they are female because their designers stated they were.
Fictional women created by art are likely and forever will be showing off some leg, torso etc. as long as the libido still exist, and even if it's gone ; It will not go away.
Diversity for the sake of it is not necessary and it is just a game after all