This is a very simple suggestion, but I believe it would add a lot of value if it can be implemented.
Courier Contract (from my understanding) are limited to Generic Cargo Holds, meaning the wrap item can only be moved in a Generic Cargo Hold.
There are many ships that have special Cargo Holds (Matar Industrials, Gallente Industrials) and other ships such as Ore Frigates, Orcas, etc.
Contracts of a singular item type should be able to be marked and categorized when creating a courier contract. This should then allow those ships to use their specialized holds for the contract.
My hope with this type of change is that it would open up the possibility of additional T2 Hulls for specialized resources. I already use the Endurance / Prospect for hauling gas or ore - I see no reason why we could not get a Covert version for example.
Would likely require enough hulls to balance the racial composition of the haulers - but there is always the option of more creative Tech 2 / Tech 1 for hauling. I think it is one of those realms they can still take much further. But when they made the specialized hold changes it was really something special.