The most important issue is that however the theist defines "free will", he has the burden of showing that free will by that very definition is supremely valuable: valuable enough to outweigh the great evil that humans (and perhaps other creatures) cause by abusing it, and so valuable that God could not possibly create a better world without it.

This to my mind is the biggest problem with the Free Will defence in all its forms. It seems pretty clear that free will by some definition is worth having; it also seems pretty clear that there are abstruse definitions of free will such that God cannot both create it and ensure it is used only for good. But these definitions don't coincide.

Well sure. But that's a separate argument, isn't it?

My point is that anyone making this argument isn't going to see Berry's argument as valid, for the same reason they are making this (flawed for other reasons) argument in the first place.

Mind you, it's still an accurate statement and a useful observation in this context.