I would much rather have a player who plays safe on my team than someone who risks everything to get every single kill. Why? Because even if you go even (which you probably won't by defintion especially if you're lowly silver like me) , or a kill per death, that makes it that much harder for the rest of your team. I can't peel a Yasuo who is 7 kills above me off my team mates and live, he will obliterate me. Yeah you're fed now but so is the enemy laner and it makes it that much harder to play the game.
So play safe guys :)