I also heard that they were originally going to be sisters.
I think they changed her design so they won't be just like the Squid Sisters. Personally, I think the design change was a good call. Not that I think this design is bad or anything, just that it helped separate Off the Hook from the Squid Sisters.
That, and our Pearl is cute.

You can repeat this all you want.
You might see her as an "Ugly Gremlin", but I view her as an adorable, sassy and energetic little Inkling who makes a good foil to Marina, has a great singing voice, and a great rapper.
And that's coming from someone who don't normally like rap.