I think the difference Orbit is talking about is constructive violence versus gratuitous violence.
Personally I think it's a question of time and place. I think non-violence is enjoyable because it makes it easier to enjoy your surroundings. It allows developers to set a lighter mood, like Portal 2. It just never gets too heavy, and at least for me, that makes me want to stick around longer.
My favourite games of all time are the Little Big Adventure games. Your BFG in that game was a bouncy ball, and it was fucking brilliant :P
Even in the less-than-lethal category, I thought playing something like Swat 3 or Police Quest was far more exciting in terms of actually shooting people, because you did not ever want them to die. Even if it was a total douche, you were still better off going for the legs and doing whatever else you could to keep them alive, while neutralizing them.
It's definitely an overlooked element to games these days, and I do think that's a shame. I don't really mind violence, but sometimes I wonder what developers were thinking. Max Payne 3 isn't exactly a game that holds a lot of irony (if it did, the writing would be easier to swallow) but if you keep shooting a guy in that game, after he's dead, he'll just wallow around on both legs and take it.
I thought that was pretty unneccessary. Instead of providing gratification that you'd killed the guy and saved your life, it just made you feel like a sick fuck for making his dead body dance like that.