In the admin interface, I can't omit fields from "admin = meta.Admin(fields=...)" even if they do have default values. If I do that, I get errors for required fields.
In my own forms, I first assumed I could just leave out fields with default values in the model, but my form.error_dict gets filled with complaints of missing required values. I don't want the default values to go through the form as hidden fields. So, if I'm not mistaken, the default values for a model's fields are not used when saving an object, and I must create a custom manipulator to do that. But is there a reason why this isn't the current behavior?