They haven't been forgotten. They've been expanded upon. Sue was originally unable to use both invisibility and her force field at the same time. Now she's able to use both simultaneously at levels beyond what she could in the past. While it's conceivable that an "invisible force screen" was her version of training wheels for using both powers at once, It's still a middle step. Johnny's whiteflame is obviously a level between normal flame and nova level. A page in a story describing Johnny's various levels and what colors mean in regards heat and intensity would help. Someone on the board here (Crimz or Ray, I think) described using the color Johnny's in that fashion. Neither is anything but an optimal level at the time which has since been surpassed.