I'm not saying it's my argument, and I'm not saying it isn't just as prevalent in *other* mediums either but I can certainly see a trend in the big triple AAA titles we get these days and putting players in control of characters who dish out brutal beatings apparently on a whim simply because that's what the market 'wants'. God of War, Assassins Creed, Tomb Raider, GTA et al. are all fundamentally underpinned by the idea of tasking the player to commit acts of increasingly realistically depicted violence. And, unlike films or TV, you are placing the burden of orchestrating these moments squarely on the shoulder of the participant. Also I'm not sure what else to call 'press X to rip opponent's spine out' if not gratuitous.
As far is it being detrimental to an experience is concerned I'm going to flag up the curious case of No More Heroes. Came in two flavours, one for delicate Asian and European sensibilities (which always struck me as faintly absurd given the reputations both territories carry for going the other way when it comes to depictions of graphic sexual content) and one for full-blooded American gore junkies. Being in Europe myself I played the former, where all the major kill scenes are robbed of their savagery by virtue of everyone exploding into clouds of magic dust, and duly had a gay old time of it carving mooks and bosses harmlessly up with my laser sword. A quick scout of Youtube tells me I really wouldn't have half as good a time of it with the uncut version, since suddenly you're jarred out of the relatively pantomime proceedings to sit through a scene where you behead an old lady or cut a girl's arm off. It's still over the top and obviously intended as satire of its own genre, but taking that leap from a cloud of fuzzy pixels to a portrayal of suddenly visceral brutality fundamentally changed the experience I was having with the scenes. One was enjoyable, the other distinctly uncomfortable. And, nine times out of ten, I am not playing a game to feel disgusted at my own achievements I am playing a game to have fun. Should saying it's a game's 'message' or 'ethos' to engender a certain response in its audience really be used as an excuse for this sort of thing? A game is specifically not a film or a book or a piece of provocative theatre. It's a game. A thing to take amusement from.
I suppose ultimately the question is whether or not one perceives these things as 'necessary' or 'acceptable' in terms of the overarching narrative construct of the piece. And obviously those examples all have particular sorts of stories to tell which necessitate a degree of violence. But you certainly cannot deny the proliferation of violence in gaming, and surely that's worthy of discussion if nothing else?
Also I'm sure someone will call me for flagging Tomb Raider up there as an example, but it generated all that controversy for a reason. Lara did get her Rambo on for the latest outing after all.