This mechanic made a major debut in Half Life, where it helped set the tone of the entire game. After (accidentally) kicking off the Resonance Cascade, Gordon stumbles out of the test lab and back into the main complex. There are a number of places in the early game where you'll see scientists abruptly yanked into ducts, ensnared and eaten by barnacles, or killed by headcrabs. Half Life was one of the first FPS games to offer this sort of scripted event, and it was a big deal. Previous games, like Quake II, relied on a silent-protagonist-against-the-world approach; Black Mesa, in contrast, felt much more organic.
It was a different time.
That was 1998. Fourteen years later, games still rely on exactly the same mechanic. The problem with this approach is that it breaks the idea of control and briefly transforms the game into a movie. Nothing kills the sense of being "in" a game more quickly than realizing that the redshirt running ahead of you or the civilian you unexpectedly encounter as you turn the corner is going to die, period, no matter what.
Fixing this can be as simple as allowing for the possibility of success. I'd argue, however, that these micro-scenes, properly harnessed, can be a potent force for increasing game immersion. Stumble upon a wounded marine fighting off an alien, and maybe it's possible to kill the alien, only to have the marine die from his wound, unless you're willing to sacrifice a medkit or have an appropriately high Medicine score (depending on the type of game).
Ideally, these sort of events would happen whether the player is there to witness them or not. If you're moving slowly through the level, maybe you only find the marine's body -- if you're slightly closer, you hear the sounds of the battle but may not arrive quickly enough to save his life. The true difference between a static event you witness and a dynamic event you play through is that the latter creates uncertainty -- and uncertainty is critical to keeping a game exciting.