The problems that I always had with WorldGorger Dragon decks. Was if your opt has a creature removal, bounce, or enchantment removal spell at instant speed with mana open to play any of those. Your going to loose all your permanents, that's if they stack there spell at the right time. Since wizards change the rules on enchant creatures, that now the enchantment just falls off and the creatures remains in play. This makes cards like Necromancy and Animate dead so much better. So basically yeah if you play the version with the creature kill, you may not win instantly but its allot less risky, because you don't take the change of loosing all your permanents. Once that happens that's pretty much game over for dragons.
The risk is not so important than you suppose. The WGD combo is very fast, but indeed, to pass it safely. You have to prepare it carefully. The time you prepare it (Abeyance, Xantid Swarm, Force of Will, Duress/Thoughtseize, etc) takes few resources, and even with a safe protection which takes tempo, the WGD combo is faster than your build.
Winning with Akroma => 3 turns
Preparing the WGD combo => 1 turn.+ 1 turn to kill.