Which is a fun part! FFVIII is as far from a stereotypical JRPG story as it gets, which I think is great.
It has Rinoa (and a couple of other lovely ladies that I will not spoil), so who cares about the rest of the cast?
Everybody that's played the game should care about the rest of the cast. Just because one character is somewhat likeable doesn't omit the game from scrunity in regards to the entire cast. And while FFVIII is definitely a non-stereotypical story, some of the plot twists that occur are just odd.
I don't see FF VIII's cast as particularly weaker than other FF games. It's just a matter of opinion. I liked Squall (eventually as you learn more about him at least), Rinoa, Seifer, Laguna and Matron. Especially Laguna. I liked Quistis in the beginning, but her story didn't end up contributing much as the story progressed. It was like she was forgotten. And while I wasn't a big fan of Selphie, Zell and Irvine, it's always been like that for me in FF games where I didn't particularly care for some of the cast members. In FF7 I didn't care for Red XIII, Cait Sith, Yuffie and Vincent (other than the way he looked). In FF9 I didn't care for Eiko, Amarant, Quiina and Freya. In FFX, Khimari, Rikku and Lulu. In FF XII, Vaan, Penelo, Basch, and Larsa. In FF XIII, Lightning, Hope (he turns out much more likable in XIII-2/3), Snow, and Vanille. And so on, and so forth.
Though even though I wasn't a fan of Irvine, I liked the idea that he didn't have a nervous breakdown during the assassination plan of Edea during the parade, but rather that he hesitated because he recognised her. Because unlike the rest of the group, Irvine didn't like using G.F.'s. And a consequence of using G.F.s was memory loss.
And yeah, there was one particular plot twist in FF8 that was pretty weird. That they were all from the same orphanage.
Since there were sparkles falling down during that scene, just like how it does when Ellone changes the past, I rather wanted to think that's what happened there, and that she brought them together that way. But I don't that's what happened. It was just a weird coincidence.
As for other plot twists in the game, I liked those. Gave you a lot to think about. Like the story overall. I particularly liked Laguna's story. Which was both funny and sad.