It may not be popular to say but the only reason any of us know who Trayvon Martin's name is presidential politics ...
Barack Obama has been a pretty poor president in general, and (based on results) an awful president for minority groups (especially black people). While I would agree with people who claim that it is not within his power to do anything about this, from a political perspective it doesn't matter. No matter how he tries, Barack Obama will have difficulty pandering to minority groups based on performance; and there will be an increased emphasis on racial incidents from the media to gin-up racial conflict to scare minority groups into continuing to support Obama.