You are quite right that the our talented, and enthusiastic artistic community is indeed amazing, and each contributor should be recognized for their effort.
I gently suggest that there are LOTS of ways to recognize such talent and effort, and that inclusion in the install .iso image is a fairly limited form of recognition.
- An add-on deb package of wallpapers
- Add a wallpaper-of-the-week link to the Ubuntu Weekly News
- Create a Hall of Fame here on Discourse or on the Ubuntu Wiki.
- Run quarterly (or even monthly) wallpaper contests here on Discourse.
None of these require any kind of approval by Canonical Staff, nor any special resources. You don’t need to ask for permission. All can be started and managed by any group of community members. Start a new thread to get your fellow enthusiasts organized.
The current wallpaper contest is run by the Desktop Team in order to meet their needs. Their need is specific, and the contest reflects that. If you have found an unmet need or a way to improve the Ubuntu community…DO it.