*Why do we retain the double letter in the suffix -less but not in the suffix ful(l)? Maybe so we don't get confused on which word it is. So we can tell the difference between, say, pickles and pickless. (There have to be better examples out there, but I can't think of any now.) To avoid having to wonder if the speaker/writer has made up a word: "Feckles? What are feckles?"