My suggestion is to make saves matter for a vuln race. I had -70 afflictive saves as a fire giant. I took disintegrates for damage. Ok. I then went down to 10 afflictive saves. You guessed it. Disintegrates for damage. Why even bother having a save system if it has no effect on the actual damage taken?
Saves.
Ice storm has always seemed to cut through saves better than most spells, whether hitting a vuln or not - which is why I recommend it over hellstream for pure damage-dealing purposes. (edit: assuming from the damage given that it was ice storm)
However, anyone who's ever played a decked ogre can tell you that saves definitely have an effect when covering a vuln. 
It is both a matter if you save the spell or not and how much a spell is safeable in the first place.
well I had 70 afflictive saves. And took disints from ice storm all day.
Saves are also only one factor in damage calculation. I would imagine there was a variety of damage dealt.
The damage I took was disintegrates constantly.
I was told when I played juhpa that ice storms would always do === or >>>. Even though I had protection, sanctuary and -70 or so to afflictive. I just stopped equipping for saves.
I've experienced the same with one of my fires. Being at -40 aff saves I decided to try -90. I vaguely remember it not being worth it so I stuck around -50 I think.
It is both a matter if you save the spell or not and how much a spell is safeable in the first place.
I would gather, then, that ice storm is not as saveable as most. I certainly recall Juhpa's astonishment at the damage Daenaer could do to him through all his protections.
Edit: icicle, however, I don't recall being quite as effective - try fighting next to big mobs to limit area attacks.
I remember this also being a frustration for Fistanlius (spelling?) when I was in NEXUS with him. Knight invokers tore him up no matter what.