One of my biggest pet peeves is witnessing something unbelievable in a fictional story because it kills the immersion experience. Plot holes and the overuse of action and special effects are usually the main culprits.
But it’s fiction, you say; it’s all unbelievable, duh. No. Believability is always tied to a frame of reference; in this case, it is tied to the fictional world, not to the real world. Take Superman, for example. Yeah, we all know people can’t fly like that in real life, but we accept that he can because he’s from Krypton. I don’t have a problem with any of his powers so long as they “make sense” in the Superman universe, but if he waves his hand and vaporizes Lex Luther in the final climactic battle, then I have a problem. Why didn’t he use this ability earlier and save everyone trouble? This glaring plot hole basically renders the entire story absurd and makes the audience feel like watching the movie was a waste of time.
“Unbelievability” can be an issue in any genre, but it seems particularly prevalent in sci-fi/fantasy and action/adventure. Now, I don’t believe that this is a problem with the genres themselves because I’ve seen good examples like Avatar. Yes, James Cameron couldn’t resist making the climax one long CG-action fest, but for the most part, the special effects brought Pandora to life without being overblown. The climax was still a bit of a stretch, but the story built up enough to it that it didn’t feel outright absurd.
Believability is totally in the hands of the creators. I would like to see them spend more resources creating tightly written plots and less on “wowing” us with action and special effects. Honestly, your mind goes numb and no longer responds to that kind of stimulus after awhile, and no amount of action or special effects, however impressive, can make up for a weak plot. Technology should be used to enhance storytelling, not as a substitute for it.