That's actually the thing.
Different ATs play differently, and I think it makes perfect sense that Storm Blast would feel terrible as a Blaster but not that bad on the other ATs.
Blasters are all about up front damage, so a blast set that doesn't do that very well does in fact feel quite bad in comparison.
It's an AT that doesn't leverage Storm Blast's strengths nearly as well as the other ATs naturally do. The most it can do is build for enough defenses so that the to hit debuffs might be meaningful, but that will rarely help the blaster do it's job better, especially on teams. Combined with the burden of the very clunky Storm Cell, well....
Conversely, Storm's slow damage damage isn't felt as keenly on other ATs, and its debuffs complement their roles much better.
And yea, obviously Storm can't hope to compete with Ice.
In addition to much better ST, Blizzard is categorically better than C5. 😏
Dramatically stronger debuffs and only requires half as long to do its work. I find C5 incredibly underwhelming on blasters.