I think it comes down to something like this: a mundane explanation always loses against a fantastical explanation.
And for some kinds of conspiracism, an accident scenario always loses against deliberate malfeasance. When a person focuses on conspiracy theories as a way of coping with disappointment or perceived failure in their lives, they create a fantasy world in which they are the hero. This requires creating villains. Happenstance events are easy to co-opt into nefarious plots by mysterious enemies, and the conspiracy theorist's diligent work "exposing" the plot is his payoff.
So yes, an anonymous group (or perhaps the US Navy, FBI, CIA, Al Qaida, the Mormons, etc) using an unknown weapon (directed-energy weapon, super-secret missile launchers, invisible fighter planes) to blow up a random jet for an unknown reason (no idea on this one) makes more sense.
So a fun Poe web app might give you a set of drop-downs from which you choose perpetrators, modes of operation, motives, etc. and generates a conspiracy theory based on it. Minutes of fun!
It's never a case of "people make mistakes, people get sloppy and cut corners".
Normalization of diligence and risk are things I deal with when I work in forensic engineering. This is the concept that everyone tends to approach what they do with a similar level of diligence regardless of the objective importance of the task. It combines with complex social models to explain a lot of incidents and accidents. It explains things such as a tanker captain exercising no more care on the job than if he were driving his own car. This is the brain's response to high-stress occupations. When you do something day-in and day-out, it becomes the norm for you. Your ordinary "Hey, this is important, we should pay attention," responses get dulled over time.
Airplane maintenance is a good example. You get dulled to the fact that you're working on a machine that hundreds of people trust their lives to a dozen times a day. It's
your daily grind, so you normalize to it. You start thinking things like, "If I make a mistake, one of my colleagues will catch it," or "There so much redundancy in these things that it's really not as critical as you'd think."
But because this fact of human nature is counterintuitive, it's hard for conspiracy theorists to imagine. It's hard to believe a designer would design something unsafe, that an operating company would allow a dangerous situation to persist, and that people whose job it is to maintain and inspect airplanes would ever treat their jobs with anything but the utmost diligence and care. These become powerful falsifying propositions for many mundane hypotheses. But it comes down to the sentiment that, yeah, you'd think these people wouldn't ever make preventable mistakes, but the fact is they do.