I remember getting a lightning bolt scroll in Act 1 btw. It's definitely not that rare.
But I agree that Sorcerer multiclassed into Wizard isn't really that great, unless you really want to try out more spells. But that has nothing to do with effectiveness.
On the other hand, there are definitely multiclass combinations relying on the Wizard spell scribing that are worth losing one feat for, e.g. Tempest Cleric.
