She'll have the opportunity XD! Very soon in fact!
I only used her when they forced me to XD. Like early in the game and when the team got split up for plot reasons. The missile base, for example. And no, Quistis, despite the tutorials from HELL and her rambling, her Blue Magic saves my LIFE during the final boss battles. Mighty Guard. Keep spamming that Mighty Guard.
Ugh, the final boss of FF9...horrible blemish on the face of an otherwise fun and gorgeous game. I just like to get through that battle and ignore all the random shit he says. Thankfully Necron's music is fun, otherwise it'd be a total bust. And awwww Vivi! He's the cutest thing ever and so sweet! But no, level, level, LEVEL for FFIX. Or Kuja will destroy you before you even get to Necron. You need to micromanage abilities too.