I think that Apple would have a lot more developer enthusiasm for this feature if it wasn’t so clear to many of us that our apps will be forced to lose features in order to adopt sandboxing. And while users may be happy about the prospects of improved security with the sandbox, I think there will be less excitement about the diminished functionality of apps whose features don’t fit nicely into the sandbox confines.
Sandboxing is a very nice idea in theory, but so far the benefits seem to be hypothetical while the costs—in features and development time—are real. Furthermore, we’re coming up on the November deadline, and Apple has yet to actually say what its policy will be.