Our University during Moodle pilot want to use it's courses to store all information in one place, including students exams answers -assignment is the useful module for this. This turned out to be impossible thanks to the flaw in the permission control.
On exams students work on the university computers without mobile information device. It is crucial to save student's work in the case of appelations, but students must not have access to their work after exams. This means that they must have permission to upload, but not to view their work. However, setting mod/assignment:view to Deny effectively prevent this, as the assignment page displays error if they don't have the permission to view. This is also conflicting with logic of permission, as they become dependent, thought it can be prevented in this case.
I think, that title page of the assignment must check two permissions and result in error only if they all are denied. If view is denied and submission is allowed it must skip the part with view of the answer (or link to file) and display the button to upload (or edit) the answer. If the question has text answer, than there will be no edition, each attempt to change the answer must start from empty field (which is totally compliant with exams system: user can change their answer for theoretical questions only on the next exam with another question, in the case that previous attempt failed), or there may be an option to allow or disallow edit old text (exams can also use a time control,).
Please take care of this issue, as this is really important to our superiors.