I've heard people say that the games don't have enough sci-fi elements, but I feel that they do. A good half of the game may be on an underdeveloped planet, but I think the sci-fi elements start kicking in after that and even invade the current setting. SO1 had very little, but it made sense. The game was pretty rushed and sort of abruptly ends since they were told to work on a planned PS1 title so soon. SO3 had sci-fi, Elicoor, then more sci-fi. Elicoor definitely feels like it takes forever the first time, but on replays it doesn't feel too long. SO4 had a little too much sci-fi, imo.
I feel that Star Ocean isn't supposed to be a full blown sci-fi RPG like Xenosaga. It's more about what happens when people with technology end up meeting those that aren't quite as civilized, and see how the two interact.
And yeah, SO story isn't amazing. I liked 2 and 3's stories (dialogue is questionable). SO4 I'll just ignore since the story and characters were awful to me.