Somehow, people are still confused as to why and if The Flash on the CW is not in the movie universe at Warner Brothers and that is because they are separate universes! That is why (supposedly) Ezra Miller’s Barry Allen (Flash) will be rocking a more tech-based costume. As you see above, this is from the Injustice: God’s Among Us video game which depicts The Flash in a more armor like uniform which is more logical when you break it down.
So long Miller’s Barry Allen scarlet and yellow suit looks as cool as the Batman/Superman/Wonder Woman/Aquaman costumes it should be no issue in the future, but the Flash is a character that can come off as campy and more silly than the others simply because of his personality alone and a bright red suit needs to be both fun, but believable in the universe DC/WB is going after.
With Allen being an already intellectually sound character, he could do what most heroes and villains have done in film and comics and that is make his own suit. Den of Geek is claiming he will be just that, a tech geek, and could likely be designing his own suit. It all makes sense.