I think this suggestion has merit. It would be useful if you are watching a movie and have the sound cranked up to the point where you may not be able to hear the phone ring. In my home theatre I have the door bell and the phone hooked up to flash an LED light on my component rack for the very same reason.
You can post your suggestion in the Idea section of the Neighbourhood.
Software changes do not occur overnight. They can take quite some time to implement if approved. Updates are usually done periodically and are typically multiple changes in the update and not just one tiny little cosmetic change.