Personally speaking, I feel like I play Sims in a way of reality to keep a progressive storyline. The Sims do have limited amount of ways of dying in comparison to the real world and death (at least in ts4) is not autonomous or frequent as it was in other series. So I have to kill a Sim or two so that my story could go "oh, they lost this family member or this person died and now love is lost or whatever the case me be".
In ts2, I killed Sims just for the fun of it and maybe that was because I was younger. In ts3, I killed Sims but it wasn't as fun as doing it in ts2. Buy now that I'm growing in my young adult life, my game play has not been about killing or torturing sims, but about progressing on into adulthood (marriage, children, working, etc.) because that's where I'm at now in life and want my Sims to experience it too. (I may be too attached to this game and playing it as a reality).
I'm not sadistic or a psychopath. It's just a game where my imagination of storytelling goes. It's where I would create a cheating Sim to marry and then see how he or her ruin the lives of those around them. Do I condone this is real life? No, but it's like my alternative world as I like to refer it to.
Sims has been a game that I use to distress after a long day at work or school or when real life is just too overwhelming and I have no one to talk to. So I'll vent and take my frustrations out on my Sims sometimes. It's great at just taking your mind off things.
Eta: autocorrect corrections
