My two cents...
Heya, fellas.
Saw this discussion on the forums, and figured I'd chime in. Since I'm in the process of trying to write a fan fiction based on the WCU following the events that take place in Prophecy and SO while remaining true to the spirit of WC, I've been trying to get inside the heads of the various groups - UBW, Confed, the Kilrathi, the Nephilim, etc. - to try and figure out what makes them tick.
As far as the Kilrathi are concerned, I tend to agree that it's in their nature to do battle - it's a natural instinct for them. Generally speaking, I don't really envision them as the kinds of conquerers who conquer for the spoils, though I guess I could see them keeping some kind of memorabilia from a defeated skillfull ally (I'm inclined to think Thrakhath would've probably paraded around with Blair's head on a stick if he could ever get it, if for nothing else than to prove to his brethren how inferior the humans truly were).
When it comes to the Kilrathi, I picture a kind of Darwinian Theory...they seem to support the idea of having the strong flourish and the weak perish - even among their own species.
Additionally, they also seem to be strong believers in their war god, Sivar, as I think a sizeable chunk of their forces all gather at designated places each year to give a ceremonial praise to their war god (a gathering which the Tiger's Claw and the Firekkans exploit in WC1:SM2). There's also the Prophecy of Sivar...whether that was just tacked on for the latest chapter of Wing Commander or not is anybody's guess. But if you follow the logic of it, it explains at least some of the reasoning behind the Kilrathi's conquering ways. They were challenged by a superior species way back when who deemed their forces unworthy to do battle with, and swore to return at some point in the future to challenge them in a final battle if they prevailed in their wars leading up to that moment, or wipe them and their victor out when the time came that they were defeated (which is what WC
focuses on either coincidentally or quite legitimately).
So you have this race of war-loving creatures who believe in the strongest prevailing...and at the back of their minds always is the fear of what's at stake should they fail.
They are, obviously, a very aggressive race and will just as easily take their hostilities out on one another if another foe is not present. Words like "honor" and "loyalty," while used by the Kilrathi, are not necessarily held in as high a regard as their notion of the strong winning out in every case. They (remember, I'm using "they" to mean on average...I'd like to think there's always individuals who don't necessarily conform to the norm) - at least the warrior class - seem to have little respect for authority (I think in WC2, Thrakhath is talking to his cousin, Khasra, and Khasra basically challenges his Lord's position after the failures they've had...he still can't understand why Thrakhath still holds the Emperor's favor as heir to the throne of Kilrah...Thrakhath's reply is that it's probably because he's one of the few who hasn't tried to murder him).
Following the defeat of the Kilrathi, I'm also inclined to believe that their whole civilization has collapsed into a state of civil war and anarchy (though I must confess I have nothing to back that up with as of yet), as they're stuck picking up the pieces, clans probably blaming other clans for the destruction of Kilrah, etc.
I can't really argue the notion of the Kilrathi having technology before it should be their time to possess it (i.e. space travel)...it's hard to say. If you take the Nephilim, there's another warring, expansionist (or at least SEEMS to be) species with advanced technology. So it's hard to say if the Kilrathi should possess it or not. If you asked them, they'd probably argue that they won the right to the technology by defeating an enemy for it, and they'd probably have a point in that regard. They don't appear to be stupid of foolish, so I'm inclined to think that they are indeed worthy of space travel....unfortunately, their nature puts them at odds with everyone else. If there's one potential downfall in the nature of the Kilrathi, I think it would probably be pride. But then, that's probably Humanity's problem as well.
So sorry for all the tangents that have come from this...but to answer a part of your original question, Shipgate - I personally (and this is just a matter of opinion, mind you) feel that the Kilrathi are conquerers because it's in their nature - they think it's their divine right. I think that's the chief reason behind it - they have a huge superiority complex. As for the spoils...I think they just take what they can use or gloat about on the way (but those are just added perks of their violent manifest destiny).
At any rate, those are my thoughts...take em or leave em.
- FireFalcon ~};^