Well I think the changes have to do with the upcoming class (druids), ice storm is one of their spells.
So maybe extending the duration of the effect is something only druids will be able to do with their enhancements.
Weather spells in general are the domain of druids, wizards/sorcs can do them but druids get the motherload of options with them. Sun and plant based spells are the other domain of druids.
Which is also why you've seen plant as a favoured enemy. Theres few plant creatures yet the vinestalkers in the fens are one of them so far.
If new spells come for druids, rangers will likely also get some of these added to their spell lists, and clerics/fvs's will also possibly get a few. Even wiz/sorcs may get specific ones.
That's my guess anyway.