Someone said Sokka was emotionally ruined after Aang’s death and hence why he died shortly after. I didn’t think much of it at first but after rewatching atla, I completely GET it. That was his little brother and partner in crime
"One team member for each element + non-bending" seems to be the writers' logic for excluding her, but that was never a rule.
Kuruk's team had 2 firebenders (Hei-Ran & Nyahitha), Kyoshi's had 4 earthbenders (herself, Lek, Lao Ge & Wong) & Aang's had 2 non-benders (Sokka & Suki).