I find it weird that cannon pairings barely get any fan-art these days, while the ones based on friendship do. :/
Fantasy is generally more intriguing and exciting than the known and established. Like the comment chain I saw on a post recently about people preferring some artist or copyright (maybe To Love Ru?) remain right on the brink of hentai because it's more attractive and will keep attention longer than if it were to go full cheesecake.