Not sure how much control we have over it, but it would be useful to add the actual brightness value to light cards. For example, z-wave dimmers. The slider is nice but in order to get the value to build scenes or scripts, one must go to the developer states interface and look up the values. If it showed on the card this process would be easier and faster.
Philips hue bulbs show no attributes at all so if this is editable, then adding the most useful attributes to various card types is the idea.