The Problem of Evil (XXVII)

[SteveII]

Such a state of affairs would result in a singular lack of morally sufficient freedom --effectively eliminating free will.

Only if you define it that way.  Plantinga does.  He says god couldn't create a goodworld with free will, because his choosing to create that particular world (knowing, as he would in his omniscience, every choice everyone would ever make in that world) would deny the inhabitants free will.  

There are two problems with that.  

One (and I want you to pretty much ignore this one, let's not have a long digression about it) is that it makes free will worthless.  I like my free will as much as you like yours.  And if you tell me this world was created by an all-knowing god, and that therefore, according to Planting's perverse and self-serving definition, my will isn't technically free, that doesn't make me like it any less.  

The other objection is that Plantinga engaged in special pleading.  If god's knowing our decisions beforehand robs us of free will in a goodworld, then it will also do that in a badworld.  The logical result of Plantinga's logic is that tri-omni gods cannot create any world with free will.  

In which case, a goodworld without free will would be better than a badworld without free will.  

So a good god, if it existed, and if it was omniscient and omnipotent, would still have created a goodworld.  

I think Plantinga's argument was that God could not acutalize a world that had no suffering and free will because:

1. He does not consider it free will if God had to contintually intervened in event as to make a person choose good (strongly actualizing).
2. While it might be logically possible that God can "pre-plan" a possible world (weakly actualizing) with free will and the outcome of no one ever chosing evil, it is also possible that he cannot actualize a real world with such an outcome. 
     a. It may be that in a particular "possible world" a person would choose good, but may very well choose evil in the actual world (he defined this as transworld depravity). 
     b. Will trillions+ of such interrelated possibilities, it is not apparent any longer that an actual world of free will and no evil is possible. 

Your conclusion that given Plantinga's argument, God cannot create a world with any free will illustrates the problem with your definition of omnibenevolence and if it entails an obligation.