To a lot of people, Aquaman isn't seen as a serious superhero because of all the jokes.
I agree that the film really need to convince the audience that he's not lame. But wouldn't Flash too get backlash if a former teen idol who's not relavant gets the role? I don't think the problems are exclusive to Aquaman only.
Can something be done to change this? Hard to say.
If Sawa or Gallagher starred in a handful of interesting independent dramas, would it change the negative opinions some people have about them? Not completely, I guess. Their works during the 90s still hunts them. The people who found them annoying as kid/teen actors, will they always find them annoying? That's quite interesting to think about.
It has been said before, but I want to bring it up in this discussion.
Whether an actor stars in bigger films or not, isn't completely related to talent. Other factors plays in, like if he has a good manager or not, if he has the right personality to be an A-lister, if he's good-looking etc.
Let's speculate and claim that Devon Sawa was a better actor than Ben Affleck ten years ago. Who would have cared? Sure, Affleck was boring and wooden in Daredevil, and Pearl Harbor. Those films are far from being masterpieces. But Affleck had other things going for him. Not only was he handsome, but he was media's favorite, and also a good friend of Matt Damon etc etc. Sadly, those things are important in Hollywood.
What about Gallagher? I think he's quite good, but not great. Am I the only one who think so? He can't be as bad as Rorschach claims.
Abrams cast him in Super 8. It was a small role, yes. Abrams was free to take anyone he wanted: an up-and-coming actor, or a completely unknown but talented guy. But he picked Gallagher. There must be a reason!
About Aquaman again. The one who's gonna direct this maybe will see something in Gallagher. Who knows?
Abrams is involved with both S.Trek and S.Wars. Let's say he will make a DC hero film too.
Aquaman? And perhaps he casts Gallagher then?