The way the game is set up it seems pretty pointless to use a dps companion I only ever use Healers and I guess if I ever rolled a healer I might use a Tank. So what is the hype with the HK-51? Seems to me its just gonna be another useless companion collecting dust unless they made the game more like Kotor and you could have 2 companions.
If you use DPS companion you kill enemies faster and with healer companion "accidents" are much more unlikely, but it takes longer to kill enemies. I use both types.
If its pointless for you doesn't make it universal rule.