In the first episode, there's a great scene where Selesia, a light novel heroine from a fantasy/scifi world, fights magical girl Mamika. Selesia challenges Mamika to consider how her claims of fighting for justice can sit next to the collateral damage (mostly caused by Mamika) that resulted from their battle. Coming from a kids' show, Mamika's fights have never endangered bystanders before - she's horrified. But the show doesn't go into the moral quandries or idealogical differences between the characters, and its disinterest in the inner lives of its cast ultimately damages the macro plot as well.
Re:Creator's fundamental flaw is that none of its characters seem to have any problem accepting the situation they've found themselves in.
Pulled violently from her fictional reality into our world, Selesia is forced to come to terms with the fact that her entire existence - every moment of joy or pain, every defeat and victory - is an invention purely for entertainment. I need her to react to this somehow, but her unflappable heroism in the face of this revelation blows a hole in any believability her character could otherwise have had.
It's not that every character needs to have an existential crisis - Meteora's ability to absorb information almost by osmosis from the world around her means she's going to process the situation faster than others - but no matter how unflappable their fictional character is (there's a recurring excuse about "that's how I wrote her! ¯\_(ツ)_/¯"), there should be stumbles. Only one member of the cast has a bone to pick with her creator, and even that's all but an afterthought.
In the most recent episode, Selesia has a conversation with the author of her novels about whether she would want to go back but there's an unanswered - actually, unasked - question of whether she can, and what that could mean for the story. She's found out that she's a literal fantasy and it doesn't occur to the show that this proactive, brave warrior might want answers from the person who put her entire world in harms' way for his own interest.
At every turn, Re:Creators shies away from digging into any of the interesting questions that its own premise raises, and as a result the things that it does bother to put the effort in for - highly-dramatic battle sequences, mostly - are airless, rote affairs between characters I just can't find a way to care about.