So coin shot says that it turns coins into simple thrown weapons. Wizards can cast this spell. Wizards aren't proficient in simple weapons. Wizards aren't proficient with the coins only they can use (if they cast the spell)? Is this right? Or is it RAI they are proficient regardless?
Wizards aren't the only ones who can use the spell, and they simply take a -4 non-proficiency penalty for using them.
What Claxon said. Sometimes that dip into another class that gives simple weapons can be worth it.
It's still kind of silly
I'm not sure why you're particularly worried about it.
So you're not proficient. It's not really a great spell in the first place.
If it is a wizard spell it is also a sorcerer spell because they share the same spell list. Sorcerers are proficient with simple weapons. Just because the spell is not ideal for your character does not mean that it is useless. As Claxon mentioned wizards are not the only one who can cast this spell. Personally to me it seems more like a bard spell than a wizard spell anyways.