Frost Bomb has a niche for Challenge Modes where you can Frost Bomb + pet freeze for tons of damage. Unfortunately that's getting severely nerfed in 5.4 due to the Frost Mastery change.
I just wish they would fix the random no detonation bug ...
It's been 2 patches now for heaven sakes!
To date, I have encountered the bug about 10-20 times. There was once, when I was fighting Mumta and none of my Frost Bombs detonated! I cast like 3-5 bombs during the fight, none of them went off.
I found some use of it on raden balls *wink*wink*. Nice burst of dmg. But true it has not much of use. LB is superior on ST and NT on aoe. And even on raden i needed to make own arcane spec to make it viable.
Unbelievable. 5.4 last patch of the expansion. It's still bugged!