I think when it comes to (certain) games, they act as wish fulfillment, a harmless medium to express fantasies or desires that most people wouldn't or can't act out in real life. We all have violent tendencies, in thoughts or actions, and a game may be a way of releasing this pent up aggression. I'd see it working them same for a racing game too: the majority of people won't be professional drivers or get the chance to drive many of the cars recreated in the game.
Now when you talk about the game Flower, perhaps many people fail to immerse themselves in the game the way you did, without an obvious connection to it. For one it's not a human character or something most people could empathise with. I've played and enjoyed it for its visuals, but I saw it mainly as a way for Sony to flex its HD muscles, cynical as that may be. And I refer to Flowers as I've never heard of the other games you have mentioned.
Also, there are games where killing is a necessity to progress, yet not everyone is going to find that the most enjoyable. I was playing Crackdown a couple of hours ago, and found much more enjoyment in jumping from building to building than exterminating cel-shaded bad guys. If anything they ruined my experience.