Wow, you all fail.  People just don't seem to understand!  These points, found in enchants, gems, inscriptions, etc are all FUNGIBLE!  If you have the 15 def here, you can drop it out of gems or other enchants and get more total benefit.  Example:  I sit at 490+ defense, I drop 2 +8 DEF gems for this, and replace them with 2 12 stam, or 2 8 hit gems, and now instead of 150 HP and 16 def, I have 240 HP and 15 def, or 16 hit and 15 def!  You could also switch out some tanking gear for DPS gear or avoidance gear to drop the defense rating.  There's no reason for a tank not to get this enchant since it is by far the most itemization points for the slot.