Armor ships: I don't see why anyone's arguing that these should have their DPS increased. Presently their base cap DPS is almost identical to that of missile frigates', and 20% higher than bombers'. After hull bonuses are applied, armor ships have higher cap DPS than all but 12 bonus fleet ships, excluding those that kill or injure themselves as they attack (and ignoring bonuses for area attacks etc). And it's not like it's hard to find Light, UltraLight, Swarmer, Structural, or Turret hulls for them to target. If anything I'd have thought a defensive-themed ship would have lower DPS. If people aren't getting enough damage out of their armor ships, might it be because they're not microing them enough to account for their short range? Note that bringing them to the front of a battle also makes the most of their durability.
Space tanks: With their low speed, I actually see these as primarily defensive ships, given they make excellent counters to waves of bombers or frigates, which tend to be among the more dangerous waves in most games. Secondarily they of course take down fortresses with impunity.
Anyway, if armor ships or space tanks are to be buffed, I'd rather the buff affect their durability than their DPS, thus enhancing rather than diminishing their distinctiveness.