After all, even The Flash TV series waited two full seasons before diving into that story, and that adaptation barely scratched the surface of Flashpoint’s complexity.
That doesn’t even begin to scratch the surface of how much Flash mythology we need to see established in the DCEU before the story can receive an adaptation.
Flashpoint is a story about Barry Allen and his long-running rivalry with Eobard Thawne a.k.a Reverse-Flash, but that character has not even been introduced in the DCEU yet.
It’s the same reason why Marvel couldn’t go straight to Captain America: Civil War after The Avengers; time was needed to flesh out Steve Rogers’ ever-evolving viewpoint and introduce essential heroes and villains to make the storyline work.