I think if DC had planned their extended universe far earlier, then there wouldn’t be any rushed attempts for a cinematic universe. Hell, if they planned their cinematic universe before Marvel did, I wouldn’t think they would do better, but I would say both Marvel and DC could’ve pioneered this cinematic universe idea.
Also, my idea for what the DCEU should’ve been is largely possible, thanks to this fan art by daniel-morpheus.
Link here: https://www.deviantart.com/daniel-morpheus/art/Justice-League-Movie-Poster-269215975