Even if I can't be a super killing machine I would like to make more damage
This is fairly important as a tank, if you're not dealing damage, then you'll only be CCing and supporting with your heal, which is nice, however a tank that does next to no damage can often be more or less ignored. Adding a bit of damage - you are a much bigger threat, so they wont ignore you once your CC is done and burst down your carry then turn on you.
As a support class you really shouldn't be trying to get kills, as a tank I wouldn't say go for the kill, or ever KS your carries, but you can add damage which means sometimes you will get the kill, you'll need to be fairly in their face anyway as a melee class so don't worry about it.