Good Themes don't justify poor writing (Chainsaw Man, Last Skywalker, and Steven Universe Finale)
A pushback against criticisms of controversial media that I hear a lot is some variation of "(x) controversial plot point fits the themes of the story" and while I respect the attention to the themes of a given work, most of the times this defense is tried it doesn't really hold up.
See while having themes are important to story's, they aren't the only thing a story requires. A story needs consistent and enjoyable characterization, it needs good pacing, it needs some tension, and it needs a basic respect for the audience's time and investment. Sacrificing everything else for poorly executed themes is like burning a forest to save a tree.
Now since I hate Vague posting here are some examples...
While there are many essays going over how CSM's ending lines up with its themes, I will just go ahead and say no matter what thematic point was trying to be achieve, it will never be satisfying to have your MC's entire story (the one readers spent years and hours of their life invested in) basically get erased from existence and rendered moot. To add salt on the wounds, this wasn't even Denji's choice, he just gets forced this ending without any in-put.
For the Last Skywalker, I get they wanted to hammer home the idea of failure being the greatest teacher, but they did it in the worst way possible. The Last Jedi took a beloved hero who was known to never give up when his friends lives were in danger and the symbol of what it means to be a Jedi and turned him into a failure that runs away from his mistakes. A story more befitting the theme was not worth destroying your 2nd most iconic character.
For Steven Univiverse, I get the main theme was redemption and Steven wasn't going to turn into the punisher, I get that and I actually love many kindhearted characters that want to see the good in others like Superman and Luz Noceda. The problem is that they had the 3 big bad main antagonists, that ruled over an authoritarian nightmare state that attempts mass genocide on the regular, and who created a superweapon out of the shattered souls fused together, completely switch their entire worldview in the span of like 3 conversations with minimal pushback. Imagine if Ozai, Bill Cipher, Belos, Voldemort, or Darkseid became good guys after a quick chat. Petty antagonists and bullies often need seasons of development to have them turning over a new leaf make sense and feel earned.
So while Themes are very important to writing, they are just a part of the building, and a plot point fitting thematically doesn't make it automatically good. When making a puzzle, a piece has to fit into the entire hole, not just part of it. Or for a cooking explanation, having the correct ingredients on paper doesn't mean anything if you burn it to a crisp while cooking it.