Yeeeeah, I know, but at the same time, it takes just a teensy bit of crazy to torture an entire crew to death. And even if it was just "temporary" insanity, that's still the sort of shit that's going to leave someone pretty fucked up in the head.
And seriously, no, don't focus too much on the characters and their "stories." That way you end up with bullshit that's more about interpersonal drama than interstellar combat.
One thing, though, HW2 should not be fucking canon, that game was a pile of shit. A big, messy pile of shit with practically no coherence. Half the time, your next objective was something that had never been mentioned before: "We need to go find the Oracle! Why? I'm sure there's some implied reason or something! Except it's never been brought up at any point! Hoo hoo hoo!"
Also, are Hiigarans and Taiidani human? I mean, obviously not all the races involved are, and Karan is the only Hiigaran we get to see in any sort of detail.
For one thing, I've noted that in just about every animatic where we see Hiigaran silhouettes: None of them seem to have hair. Could just be cultural, but seems a bit strange that, as far as I recall, it applies to all of them.
Also Turanic Raiders? These guys are awesome. Fucking space pirates who never surrender. They're definitely not human, though, in one ship description it's mentioned that they're in "liquid membranes" inside their ships. Could just be for the sake of negating some of the effects of heavy acceleration, or it could be because the fuckers are some sort of crazy space-fish-men.