I agree with Joe's last comment regarding the 'social' vs. 'societal' issue. However, in response to his example on the -al adjective system being flawed, those particular words are formed as such because of their roots in Latin -- 'primus' and 'primalis', and 'crimen' and 'criminalis'. Those words were transmitted into English through French, which had modified the words into forms very similar to our own modern ones. I don't know much about Latin, but I believe the suffixes took different forms because of their base words.