I've noticed that PNG files are gaining in popularity but its a slow process. Some of my PNGs are less popular than others and I can't see them in a normal search, but selecting the transparent background option brings them to the first page. That must be how customers are finding them and suggests that customers are gradually finding the transparent background option.
Of course it would be excellent if Adobe could issue some newsletter or announcement to existing and potential customers but that doesn't yet appear to have happened. Fingers crossed it happens eventually because I'm sure customers will be delighted. Quite why nothing has been done yet is beyond me.