Hard links don't work across mount points. So if the user picks a wallpaper that does not reside in his/her home folder it may not work depending upon how their system was set up.
For example I had a system where most of my image/music data was on a separate mounted volume from my home directory. Hardlinks wouldn't work in this case. Symlinks would but then you're back to the loss of wallpaper on delete issue.
Hard links don't work across mount points. So if the user picks a wallpaper that does not reside in his/her home folder it may not work depending upon how their system was set up.
For example I had a system where most of my image/music data was on a separate mounted volume from my home directory. Hardlinks wouldn't work in this case. Symlinks would but then you're back to the loss of wallpaper on delete issue.