just look at this face

he's a perfect Sokka.
browny? yes. eyebrows? check. relatable to the audience? you've seem him take an Oscar. totally ladies man? you bet!

sure, he's a bit tall and older, but that's nothing a good director and make-up artist can't fix.

maybe if they hadn't cast a six years old for Aang and a white jailbait harrypotter reject for Katara it wouldn't have stand out so much.

but this guy is perfect for Sokka... I can't imagine him acting out as a emoZuko...