I though so as well but the added armor didnt make go OMGWTFBBQ

Here is my reasoning.

With 5 points in toughness I'm @ 65.76% midigation
with out the 5 points im @ 63.94% midigation

(Obviously this is with frost pres up)

That being said with those 5 points I am now able to...
Do more AE dmg = More threat
I can heal my self every min (Plus burns up a bloodrune fast so I can keep Parry rating high)
picked up wandering plague..

Like I said it might not be the best build ever but it seems to be working for me and the extra midigation is kinda a joke
lets just say a mob hits you for 10grand which is obviously a shit ton but this is for simple numbers Im only saving 200 hitpoints....If I cant make it due to 200 hps then obviously the healer isnt doing his job.

Does this make sense or is my logic totally flawed here?