The most common reason to voluntarily sign over rights is for an adoption to take place, usually by the custodial parent's new spouse. (wisegeek.com)
By signing over ownership to the trust, you no longer own your life insurance policy and therefore, the benefits are not subject to estate tax. (mozdex.com)
However, in signing over their digital rights they do so without understanding the implications. (qaeducation.co.uk)