For me, it's been the exact opposite (and I've played a lot of 4e Wizards, sadly). Range 20 > a couple extra points of damage, most of which is mitigated by the fact that it's a ranged basic attack (so it benefits from Bracers of the Perfect Shot, amongst other things). Also, many enemies have an annoying habit of leaving the cloud before their turn starts, due to other enemies using extra move-granting powers to get them out (or worse, those same enemies will start using similar powers to push/pull your allies through it).