Well, originally, you could tell they had certain archetypes they wanted for certain companions.
Melee DPS were all supposed to be Assassin/Shadow based in gear.
Healers were all Operative/Scoundrel based in gear.
Ranged DPS were all Gunslinger/Sniper based.
Ranged Tanks were all Powertech/Vangaurd based.
Melee Tanks were all Juggernaut/Knight based.
The funkiness is when you get companions that are supposed to be things like Mandalorians or Troopers but are trying to be fit into roles that aren't archetyped for their gear. There is no reason Elara couldn't be a Commando Healer, but all they did was made it wonky. It's even more difficult to gear certain characters weapons... like Snipers on the Republic (Risha) or Gunslingers on the Imperials (Vette/Temple). And of course Droids, or half the Bounty Hunter Companions.
It's not really difficult to gear a Sniper type companion on the Republic side. Most gear that they share are the same as Gunslingers and Scoundrels. The only difference is the weapons. And even those weapons can be found via Drops, Armstech, PVP Gear, and Daily Quests on Belsavis at lvl 50.
But considering the Archtypes, There is a few things I noticed that are just either passive or cenimatically viewed are some of the weapons on the companions that aren't really there.
For example. Imperial Agents with a Blaster Pistol but they don't really carry one as a side arm.
Kaliyo has a Shotgun (Scattergun) when she does a certain ability.
Just noticing things like these could make you wonder why aren't these actually on the characters or companions. Is it because of the Extra Stats they may carry might make our characters or companions over powered? or Is it just for cosmetic reasons.
Either way you look at it, We're still gearing them as we level up, til we hit 40 then it's all orange PVP gear for the Arch Class they are.
Qyzen, most of the Trooper companions plus Torian Caldera would all wear the Bounty Hunter / Trooper pvp gear.
While Mako and Doc, wearing the Field Medic PVP gear.
Then once you hit 50 then we start the gearing process all over again. With the Raiding gear. For those who raid.
I for one will be glad when they do come out with Companion related gear. Specifically for our companions like the Raiding and PVP gear.