As child themes are becoming the way forward how about a change to the WordPress core Appearance menu?
A lot of users do not use a child theme as they might find the creation a bit daunting, so why not make it more friendly.
Theme developers can then include a child theme folder or zip in the theme, it could even be a condition of acceptance to the themes directory that themes must be "child theme friendly" and include a built in child theme.
A core function that will look in all theme folders for a folder or zip post fixed 'child' so inside the twenty eleven theme /twentyeleven-child/ or twentyeleven-child.zip
The admin can select from the list and deploy the child theme, if the child theme folder exists a message 'The Child Theme already exists', if not the child theme is created with the contents of the folder or zip!
In the Appearance > Editor when looking at theme files have an option to transfer to child theme, so if I was looking in the editor at twenty eleven, I could select footer.php and "Transfer to Child Theme", the code would look for a folder 'twentyeleven-child' and copy the footer.php across if the file exists over-write if not copy across