Specify custom field Visibility/Required on Create&Edit / Issue and SubTask screens

It would be very nice to be able to config custom field visibility and Required by Create and Edit screens for Issues and SubTasks.

The only way to do this w/o modifying JIRA code that I've found is to muck around with the createissue.jsp and editissue.jsp (still haven't done this for sub tasks). However, this is extremely client specific and makes upgrading (where these jsp's are modified) a real hassle. It would be much nicer to add extra options to the admin section which allow config of field visibility/required by create and edit.