Your container combinator provides the container inventory, but it looks useless — we can connect that container with a red/green cable and check "read content" option on the container.
Why have you added this SAME logic to your combinator?

P.S. Other signals are perfect!

Because it is not possible to read AND WRITE contents to/from a requester chest. With this, you can do both. It will also provide a means to gather information on containers that do not allow wire connections. Not sure if there are any/many, but this will do it