Thorns damage and rune "Reflective Skin" - what's WRONG?

Hello everyone
Neither in the Bombardment set, nor in the Invoker set, there is an increase in damage from thorns when activating the Iron Skin skill with the “Reflective Skin” rune.
If this rune increases the thorn index by 300% (and when it is activated, there is really an increase in the base white thorn index), then why is there no increase in damage by 300% ?!
Why then do this skill at all, if it stupidly does not work?
If it worked, but Invoker or Bombardier would become excellent top characters. And so the characters with the paragon 13100 stupidly can not even close the 141 great portal.

Is this a bug? Or does this skill somehow work differently? For example, purely on reflection? Then why not change the name of the rune, so as not to mislead people? ^)