Well, that's not entirely accurate. There are still plenty of powers out there that deal damage dice of damage upon entering a zone, and the new cloudkill is actually pretty potent. If anything, this spells the end of the Staff of Ruin necessitation for zone wizards.
For those not in the know, you can find out here: http://www.wizards.com/DnD/Article.aspx?x=dnd/dra/201107wizard
Honestly, I'm not entirely sure how I feel about this. Letting non-essentials wizards pick their own cantrips is a nice bonus, and Elemental Maw actually got an UPGRADE depending on how you look at it (Hint: It requires Spell Accuracy), but all in all, the Slide Spam build-aka the one I'm playing in another game I'm in-took a seriously heavy hit. Not only that, but wizards can no longer auto-obliterate minions left and right, with the vast majority of powers that deal damage from a zone being changed from start of turn to end of turn.
It's certainly true that the existing wizard powers were way too strong, and the modifications to Stinking Cloud and Cloudkill, not to mention Flaming Sphere, do address the Wizard's propensity for insane amounts of autodamage. But I'm left wondering if it isn't a little too much. What's odd is that since the article couldn't address every power, anyone who's playing with anything outside of Core will just take Furnace of Sand, which is now demonstrably more powerful than most daily powers.
I think it's a step in the right direction but also most likely a step too far. Damage once per turn was definitely necessary. ALSO making damaging zones into static damage, so that Cloudkill can deal a maximum of 20 damage if you just happen to end your turn in it, was probably too much.