I know i can output separated pdf's using the print option in indesign. But why is there no way to output for example only the black channel as a pdf in the export section?
I work with prepress at a printer and sometimes we get jobs that we will only change the black plate when printing editions. Would be easy for our customers to be able to export the black channel only. we also have a nifty tool in our prepress system that merges the default edition with all the black plate editions so that the customer can see if they did any misstakes when producing the editions.
Will there ever be such a function in the export settings?
I Think it's more your job as the printer to extract the black channel from the client's PDF than it is for the client to supply you with a black-only version. It's an extra step for you, but you have the prepress gear for doing the prepress work, and the client is responsible for the design. That's how it's done where I work, at any rate. One CMYK master PDF, and one CMYK PDF for each version. The workflow separates the black from the version and it gets (virtually) double-burned with the CMY from the master.