yes u can not work with out an IP even if you are not connected to the internet ,let say that u have a large Network with many no of Routers in it,and many subnetworks ,if one PC in certain subnetwork wants to communicate with another PC in another subnetwork ,here u need to send the MAC and IP addresses of the destination,while the destination MAC when passing the Router is always the next hop not the final destination MAC of the PC u want to communicate with from this point u can not communicate with the other PCs in the other subnetwork
another point that what ever the model is,the data unit within the layer must understand the upper layers protocol,while we have only one standard in both whether u use the internet or not ,here is also another reason for use of the IP while not connecting to the internet,wish the message could be arrived