Require packages that have USE-flags to provide an explanation for each one. Probably should be some centralized database that the ebuilds could refer to in order to avoid dublicating the explanations for gnome and other common flags. This USE-flag information should be accessible something like: emerge --explain xorg-x11 resulting in a list of the use flags with a short explanation what each the flag means. If that's too much then perhaps gentoo.org could setup a wiki for people to fill out this kind of documentation? Reproducible: Always Steps to Reproduce: 1. 2. 3.
You mean like 'emerge gentoolkit && equery uses xorg-x11'?