There are enough players that are already annoyed with really low level wizards having crafting badges that don't match their world, allowing zafaria crafting to open up would likely cause an outrage.
While having deer knight or other spells would be nice at the start, odds are you won't use them until Marleybone or Mooshu anyways as that's when you are actually getting enough pips to use them.
There is also a certain charm, at least for me, in having to use the regular spells for a while. Getting the best spell in the game (arguably) right at the start might feel nice, but it trivialises the play experience.
