Ah, young Archon, the humble (hah) Kabalite Warrior is not a single-role trooper, and the number of them you pick up actually determines their use. 5 Kabalite Warriors are wonderful, for instance, when loaded onto a Raider, packed with a Blaster AND Blast Pistol, and deepstruck (in large numbers, i.e., 4-6 identical squads) into an opponent's face. This small, 145-point squad is essentially an extra Ravager, with shorter range (but more aggressive deployment options and higher durability, as Deep-Striking actually allows you to avoid 2 turns of fire from the foe, and pop in to nail him when he's off-balance). The 40 more points, however, accounts for the fact that the Raider/Warrior Darklight Bomb (Ooh, did I coin a phrase?) can target and neutralize 2 separate vehicles at once, and ALSO counts as Scoring.
So what if the enemy fires on the Kabalites? They're 85 points, and annoying enough to demand attention (and by annoying, I mean, 'Oh God, they have good odds of killing a Land Raider, someone do something before they shoot us again!'), yet cheap enough to spam. Deploying them out of the Raider forces an enemy to divide firepower, which is almost ALWAYS a Lose/Lose situation for them, as well:
"Hmmm.. I can either fire my meltagun into the Raider, and probably waste all my bolter shots, or I can fire my bolter rounds into the Kabalites, waste the meltagun, and may not kill them anyway if they Go To Ground.. " There's 3 different wound allocation pools in there, after all. Someone wounds you 9 times? Lump 6 on your normal Kabalites, 2 on the Blaster/1 on Pistol, or vice-versa, and you stand good odds of surviving to demand another doubletap. 2 squads double-tapping 5 T3 85-Point idiots Going To Ground? That's a whole lot of wasted effort, baby.
If you like bigger squads -- i.e., Raider Boats of 10ish, Splinter Rack Raiders are a fantastic compliment, and allow you to zoom around and mow down infantry and MC alike. These usually run 185 with the Raider, and allow you to pack a Blaster for some good AT punch, when combined with the Raider.
The 20-man Kabalite Squad is also kind of cool, and I like them as delivery systems for Webways: You attach 3 Haemonculi to 'em, making 'em Fearless, deploy aggressively in cover, and march forward to dump 3 Webways by keeping the Haemonculi themselves outside of the cover, so when they detach, you can drop your Webway Portal without being held back by DT checks.
Don't knock any of the Warrior load-outs until you try them. Presumably, a Venom/Blaster/Pistol combo would provide good AT with a double-Splinter Cannon vehicle, and that's fine. The only reason I could care less about Venoms is because I carve beautiful sonnets to the glory of Darklight weapons into the backs of every T4 IC and Monstrous Creature I encounter, and murder hordes with my Razorwing Jets.