Eh, I think that's making a bunch of leaps. It's just as likely that there was a need for a recurring mechanic just for those scenes and someone said "hey, let's make her sexy! And while we're at it, we can tie her into it, let's say it's Cid's granddaughter". Based on interviews and whatnot, I really don't get the impression she was ever intended to be a major character at all. Basically a slightly less crazy Chocolina.
After they come up with the sexy design, again speaking to Japan's lack of social awareness, they probably thought she would make a good selling point, so they made her the unofficial mascot.
I'd be surprised if she has anything to say in the story once you leave hammerhead.