Even if people did trade to such an extent why would someone just hand over a potentially expensive cargo container when one could just use some logic 101 and a couple USDs? Dock here to get cargo, dock here to receive cargo. Trade complete, would you like fries with that?
I think the biggest utility of cargo pods comes in the form of ORGANIZED trade ships.
Cargo pods all hold a certain amount of materials. Now set your mining ships to filter their product into different groups and ship them off to different containers.
When they're full, just dock them at the home base.
When you want to sell/trade/ or use them, just pull a pod from the appropriate yard and either pull your supplies or just dock it to the cargo hauler.
That way you can make several stops along the way and sell/trade different types of goods without having to sort. Just get to the destination. Hit the "pull cargo from pod 3" button, and sell your load of cannon computers before moving off to the next sector to unload some hull blocks.
It keeps everything stored, measured, sorted, and Organized.