I only caught the end of the show, but I saw one guy (not sure who he is) saying that they think the audience wants them to kill off characters. He said that we would probably think it's more believable if some of them got killed off. I sort of disagree with that. Yes, some people will have to be sacrificed, they are stranded on an island with no medical help, monsters, etc. However, if it's the main characters they are going to keep killing off, I may just lose interest after awhile.
When the show first came on, of course we all watched it because of the storyline. Since then, we've become attached to these characters and it could ruin the show if they kill too many of the main ones off. JMO.