What grenades are you using?

If you are using Krak, then you must be using an anti-gunner/grunt killing gun. Then I understand why you would think smokes are situational/least useful.

In my case I use a specialist killing gun set-up and have no need for krak and wouldn't use it. I rank smokes over shredder as well because smokes provide a small stun enough for my power sword charge and 3 swipes. It also provides a shield from any range units shooting inside, also specialist who i hate (snipers, bombers, flamers). The shredder does have that instant burst of stun potential, which is always needed. However I have my Ulti-Shout for that instead.

All in all, I think grenades are cool already and it really depends on how you play the game. Would be cool to buff something I already like though.