The link text of the link field does allow to use tokens, but the url does not.
A use case example is using the link for a sharing function where the link is
http://twitter.com/share?url=[current-page:url:absolute]&text=[current-page:title]
and the link text "Twitter".
It does not appear logical why I can use tokens for the link text and not for the title. Therefore I marked this as a bug.