Agreed ...
But still dont see any reason to restrict that mechanicaly.
If you demand it ...
Please quote me any rule that strictly forbids any Wizard to be so faithfull and religious, so he manage to reach any deity that would be able to provide him such powers.
Self-moderation is the key here. :P
The simple fact that cleric spells arent in the wizard spell book anwsers that question for you.
