In her defense, Rinoa was SUPPOSED to be a spoiled little girl playing at being a rebel. She's NOT a TRAINED KILLER FROM CHILDHOOD like all the SeeDs; she was MEANT to be the one that was innocent, different, and the one that saw the world in a different, more optimistic, "we can CHANGE things if we try!" way. I do think that Squall did a 180 and randomly fell in love with her, but that doesn't mean that RINOA did it; that was Squall being OOC, not a problem with Rinoa as a character. Rinoa as a character falling for Squall was totally IC for her; Squall feeling the same way back is HIS problem, not HERS.

Personally, I think Rinoa's character was fine as it is. Squall is the one that needed work, bad.