Their survivability isn't as good,
high DEX gives higher defense rating, they are hard to be hit; rouges don't mean to be tank anyway, good movement and invisiblility make them easily move in and out of the sticky situation.
Archers mean to stand back, high defense is more enough for their survival.
as less overall damage, rogue can do fighter level of damage with backstab; archers need more powerful bows!!! if there's unbalance, it's that we rarely see bows doing as much damage as melee weapons.