The whole purpose of this menu idea is to make sure agreements are made and put into effect without either party being screwed over.
We've all seen a billion threads here about so and so getting screwed over or whatshisface running off with HQ when it was agreed to be traded anyways, etc.
I think it's a clever idea and would nip alot of drama in the bud without the need for the mass Q_Q GM calls for those who aren't trustworthy, both customer and crafter alike.
There really should be no harm in a mutual agreement when it comes to crafting services and fees. Especially when it's put into systematics that prevent both parties from getting the shaft from malicious intent.