Its two keywords give it more value, both of which are especially useful on an Uncommon. In fact, because of the keywords, this is far superior as an Uncommon than the same on a Common. It discards Rares and chains Aqua triggers.
Additionally, the cost being almost evenly split between two resources makes it easier to play than a card that costs 33 of a single resource. You can't look only at the damage/cost ratio. Granted, that it uses the same resources as most Aqua makes it more difficult to chain Aqua triggers, but there are plenty of Common Aqua cards that cost no more than standard production.
All of this is not to say that it couldn't stand to be buffed, but it's not as simple as you make it out to be. I agree that it could stand to hit a little harder, but do take into account its utility bonuses.