Most of the time, detailed futuristic scenarios are not presented with the intent to say, "exactly this will happen." Rather, they are intended to say, "something like this will happen." Many people have trouble with purely abstract thinking, and benefit from the clarity of specific examples. If you make a general statement about the dangers of reckless scientific experiments (for example), it is likely that many of your listeners either won't be able to connect that to specifics, or will come up with examples in their minds that are very different from what you meant. If you write a novel about it called "Frankenstein," those people will get the point very vividly. The novel has approximately zero chance of coming to pass exactly as written, but it is easier to understand. Unfortunately, the detailed approach carries with it the very real danger that some people will take the fictional details to be the substance of the claim, rather than the abstract principle that they illustrate.