It does not feel to me as if the impact of my skills is too weak, but then again, I hear a big explosion and see a giant fireball and a really big dent in the opponent's HP with each Fire IV, so yeah

For classes like my NIN, BRD or lately MNK I do not expect them to have crazy sounds or animations. Shooting an arrow or punching with my bare fist SHOULD not sound and look the same as if I just threw a bomb at the boss.