Guys, there aren't tanking mods because AUGMENTS and ENHANCEMENTS have tanking stats. Not to mention blue/purple crafted armor. Mods are just NOT for enhancing those type of stats.. if you have a crafted item that crits, i.e. has a item modification slot, it can vary from augments, mods, etc. Depending on which one it is, is the type of modification you can add to that slot.
So THAT is how the crafting system is devised. Most orange armor or crit'd armor has extra slots for item modifications. The tanking stats are assigned only to augments and enhancements (as far as I can tell), while the stats in general + armor go with cybertech mods.
Hope that clears this question up.
This is flat out untrue. There are plenty of modifications with tanking stats that drop from quests. For example, the 2+ heroic daily on Belsavis, A Lesson Is Learned, rewards several mods including this one: http://www.torhead.com/item/92iHI9E