Here's a a feature suggestion for xenForo.
If xenForo dev's have made up their mind about not wanting the star rating to come into the forum, then why not like/dislike thread. And it would display how many likes (up votes)/dislikes (down votes) each thread would get.
Sometimes the forum needs these extra features because it can add more realism,social,etc to it instead of there just being random messages, you know?.
Please look into this.