In a non-interactive story, the events are obviously set. It doesn't matter how much I want, say, Wash to survive in Serenity - I can't change the movie. I can press pause in the DVD, I can rewind, but it's still the same inevitable ending. In a computer game, though, I could save before that section and find an alternate course of events that saves Wash's life. (unless it was an inevitable, scripted, non-interactive event, of course). If I can backtrack and save or doom him without significant consequence, then he exists at my whim. I might save him if I like him.
Similarly, I can't imagine myself sitting down to watch a movie called A Deranged Handyman Walls Up Six People In A House And Watches Them While They Starve To Death Or Light Themselves On Fire, but that's the basic 'plot' of a lot of games of The Sims. The lack of consequence, of finality, devalues the life and death of the characters, and also removes a lot of tension. If I can 'play' with a character, in the sense of treating it as a toy, then it's going to be very hard for the game to build a story around that toy.
On some tv shows, say Star Trek, I know the good guys are going to survive and beat the bad guys. The question is not if, it's how - it's serial fiction, with no real conquences, and the status quo is always re-established. Other shows allow change, and they tend to be more involving.
Tabletop games have a sort of negotiated finality. Your character might die permanently, but there's a certain amount of leeway and arguing with the Games Master (either explicitly or implicitly). Still, it's very rare for a game to go back and replay an event after it has happened. There's finality. However, the immediacy of a tabletop game means that it is much harder to use the conventional elements of storytelling to make a good story - dialogue is unpolished, it's hard to develop plot and character coherently, special effects are limited and so forth. It's very hard to extemporise great literature, after all.
(Aside: I wonder if play-by-post games might not be the most immediately recognisable form of 'art' or 'high-quality game'.)
So, traditional non-interactive stories have polished stories AND finality.
Table-top rpgs - actually, let's be more general, and say human-moderated interative fiction - have finality but are limited in their ability to have polish.
Computer games (or artificially-moderated interactive fiction) can have polish but rarely have finality.
There are ways around this limitation. You can add greater import to the player's decisions by having the consequences be unavoidable, even with the ability to backtrack. If I have to choose to let Wash live or die, that's really not much of a choice if 'live' just requires me to backtrack to a better save position and keep a health pack until the bit where he gets mortally wounded. If, on the other hand, my choice is 'save Wash or save Kaylee', then backtracking doesn't help me. The game now has a branch-point that I can't avoid. There's finality.
(And now I'm coming close to arguing that games like The Secret of Monkey Island are our best examples of interactive fiction, which I don't agree with at all.)
I wonder how, say, a two-hour computer game would play. You can't save your place, but you do get to make decisions about the course of events. Would making the decisions irrevocable within the game make them feel more meaningful to the player?