About:config is currently a jungle.It's something that we simply inherit from Mozilla. Some useful settings from about:config are actually mirrored in Gconf (for example /apps/epiphany/web/smooth_scroll), but I don't think we would gain much by mirroring all of them. It would become a jungle.
Taking only the relevant banana trees from that jungle and putting them into gconf, while it increases the number of gconf options, would be great usability nonetheless. And about:config could instead point to a semi-blank page saying "no, use gconf-editor!"