The dev team did mention that they didn't want to add sharks because real life sharks are actually killed and hunted a lot, but they're still dangerous, so they decided to not implement them because they didn't want to make them too tame and have people IRL think that sharks are friendly, and they didn't want to make them too aggressive and have people try to kill real sharks so that people don't get hurt. I do like how the Elder Guardians are like mini-bosses, and having more extra strong mobs in the overworld would be fun, while it might be too late for a Kraken, a desert boss would definitely be nice, it would add to the lure of the desert.