Kill la kill is about discovering yourself after trauma (philosophical perspective)
Depressed people usually "lose their way" and get alienated towards themselves and their surroundings . They don't know who they really are or what is their true goal. They lose passion on a level that they may lose the ability to do anything in the world. Even getting up in the morning is a dreadful task. Their trauma is a part of their identity. An abusive mother is not just someone who hurt you but she is a part of you and your memories are full of her.
Ryuko lost her father and later finds about her abusive mother. She is enraged with a fuming revenge but slowly finds out that she is made of the same fibers that she hated the most. She is both the fibers and herself. Satsuki is the more responsible girl who supressed her emotions to reach her revenge. She thinks becoming strong and orderful is the way to defeat the evil in the world. They both get naked to find the truth but Senketsu and junketsu are different. Senketsu is their father's soul which he made it with his last breath. For Ryuko getting naked means that she must give blood (destroy herself). She briefly turns evil because of losing herself in a new form.
The idea of getting naked to reject society and to discover your own powers is the core idea of Nietzsche. Your true self is never in the past but it is what you struggle to become. He says:
" For your true self does not lie deeply hidden within you. It is an infinite height above you – at least, above what you commonly take to be yourself." and
"You must have chaos within you to give birth to a dancing star."
And if you think about it, Ryuko turns into a giant glowing star at the end. For me the message is beautiful : if people become themselves the world will not fall in to evil manipulators hands.
I believe this is Neon Genesis Evangelion for the nihilists. There is no Genesis or Evangelion in this one. It is chaotic. At the end even the main characters seem confused about the main message but this is the writers trying to hide the message. It is chaotic and it has Mako in it. Mako represents the chaotic good in the world when the evil people design their plans according to their logic some Mako just show up for no reason. Their evil logic will fail by the most natural good things.
This is why I love this anime and it has really good action and plot supporting the message. The anime uses freedom of will to change logic. Like the creampie scene in episode 4. The animators are their true selves and don't give a f about how other people "judge" them.