From the Release Notes:

Ranged weapons have been added to many ranger and rogue hirelings, who will predominantly use them when Standing their Ground in aggressive mode while an enemy is outside of melee range:
Rangers: Tarlov Snowtrack (level 23)Rogues: Sullivan Tiehl (Level 20), Reaver (Level 14), Istrin Teken'ar (Level 11), Olivia Whurgan (Level 7), Talonia (Level 4)
1st) Many? Funny definition of many!

2nd) NONE of those Rogues are Mechanics?
Sullivan is an Assassin
Olivia, Istrin and Reaver are all Acrobats
Talonia has Haste Boost so is possibly also an Acrobat {Only Lvl 4 so no way to be certain}.

So of the FIVE Rogue Hirelings you've given Ranged Weapons to...THREE of them are EXCLUSIVELY Melee Builds?
Sullivan is the only one who may do decent Ranged Dmg {Decent for a Hireling that is}.