Superdense coding allows sending two bits of classical information by only sending one qubit physically. Ideally this will double transfer rates. And in any case it provides another "modality" for data communication, which may provide tradeoffs that have benefits in other directions.

I'm pretty sure (haven't been in the field a while) that superdense coding the densest coding that one can gain using quantum entanglement.

https://en.wikipedia.org/wiki/Superdense_coding