Version 0.12 of graylog2 doesn't appear to parse facility/file/line from the additional fields, so I guess (unverified) that support for gelf v1.1 is being introduced with the yet-to-be-relased 0.20. Assuming that it works without them in the new version I'm not personally against removing them since we will probably upgrade soon, but I worry that maybe they would still be useful to others.