I'm with you defending stuns in the set, but I think this does sometimes get confused with the power Stun.
The power Stun didn't do anything that Total Focus doesn't do. (I'm pretty sure that is correct)
That said, having two big 100% chance for stuns had their uses, especially after the slow Energy Transfer implementation.
With both quicker ET & TF.. I don't think Stun is quite as critical as a power. Many of the other powers also have some stun with ET and BS both at 60%, mag 3, 9 to 10 second-ish.
To all: I think stun resistance affects duration not if it can be stunned on not. Can anyone confirm?