Why are Payment Term and Currency Code mandatory fields in the AutoInvoice template?

Summary:

Why are Payment Term, Currency Code, and Currency Conversion Type mandatory fields in the AutoInvoice template? Given that these details are often predefined in system configurations—such as Customer Configuration, Transaction Type, and other setups—why doesn't the system automatically fetch them like when we create transaction on UI? Is there a specific reason they need to be explicitly provided in the template? Additionally, is it possible to leave these fields blank?