We switched to a new JPEG engine in MC18. It was a little faster and works on Mac.
Unfortunately it doesn't have CMYK support. The developer was willing to add a way to get to CMYK JPEG data for a price, but it would still require us to do the CMYK handling.
So it might happen in the future, but it's a little complicated. I decided it was best to wait and see so that we could gauge the need and demand.