I have noticed that may new WP-users are unaware of the virtues of childthemes, when they start to adapt their site to meet their needs.
A large number of new users find it difficult / cumbersome to create one.
Much time is taken up in forums to explain 'why-and-how' to install and use a childtheme. More time is spent explaining 'how to fix things' after a mishap.
I feel it would be an improvement if WP would 'by default' include a simple and hassle-free option to create a childtheme. This should be 'brought to the attention' of the user when a new theme is installed or another theme activated.