I t would have to be rewritten to allow illusionists and to allow rangers access to mage spells. It is hardcoded in that only magic users may use magic user spells. If you give another class the ability to use them, either it won't work, or you have to take the ability away from magic users.
Besides, I already feel like I control the destiny of DC far too much. Switching over tto 1e as the default would be beyond what I'm comfortable doing with CocoaSpud's program, especially considering recent events.