You can do HM EC with rakata. That's what everyone was doing when it was 1st released, and ppl , myself included were clearing it all in 2hrs. With augmentation kits(released after EC), it is now easier than ever to clear HM EC. Now players got Full campaign gear and are doing HM TFB.
Story modes are for the casual players who just want to see more content, without feeling being left out when a new operation was released.
Simple to understand yes?