I mean, turning into a vampire is a coded thing in pop culture, turning into a mermaid not so much ? The other way around, mermaid turning human, feels more common.
I see the kelp as mechanics to play catch-up with sims you already created but in hindsight should have been mermaids all along.
Unless I'm missing something and there really is a deep lore behind the magic kelp, and not just "oh yeah mermaids they've always been there on Sulani, that guy here is Jim he was born with the tail, you just never saw it before because he's shy."
Maybe in realm of magic you could get another scenario, buying a potion off a witch to transform, w/ animations et all.
