I know a lot of people have a problem with this seemingly darker/more serious look for Aquaman, but keep in mind that many of the GA seemingly don't take him seriously. Snyder probably wants to go all out to insure that these same people leave the theater with newfound respect for the Atlantean. I hate to say it, but having him shout, "Outrageous!" might not accomplish that. So honestly, I can see why they'd go for a much more serious version.