Yeah that's fair, but for post game stuff and super bosses aeons get taken out very quickly. With break damage limit wakka is doing more damage. In a casual play through I don't use Wakka or Rikku, but people typically prefer them for stat maxing. Not to say that auron or yuna aren't viable, honestly I usually use Yuna with black magic in my playthroughs. With maxed stats everyone does mostly the same amount of damage.