When viewing a release where a recording has been associated as an instrumental cover performance of a work, currently the lyricist information (if present) is displayed on the release page. However, if this is an instrumental cover, it presumably is without lyrics, so having the name of the person who wrote the lyrics seems a bit pointless.

See http://musicbrainz.org/release/ce6b4955-080b-4d0a-8e77-634aa0d9c5a2 for an example.