Quite often there are certain products which require a unique shipping method not applicable to other products in the store and it would be good if there was a way of customizing the shipping options at a product level.
For example a printer may offer signage or vehicle wraps as a part of their offering, these products would typically need to be professionally installed. A shipping method for installation isn't relevant for other products in their store such as business cards and brochures and equally the shipping applied to those products (typically a courier service) wouldn't be relevant to some signage and vehicle wraps. Therefore being able to applied separate shipping options to those products would be invaluable.