Probably nothing, but then this feature isn't aimed at people who have used emacs for years, and who like and effectively work with elisp. I on the other hand,

Probably nothing, but then this feature isn't aimed at people who have used emacs for years, and who like and effectively work with elisp. I on the other hand, am very familiar with guile, I don't particularly care for elisp, and I would like to be able to customise my editor more comfortably. For me this is great.