We've seen a lot of live-action adaptations, whether in the form of movies or shows. Some of them were regarded as successes, and some were utter disasters. One of the important factors that needs to be considered is accuracy, and there are a couple of reasons under that quality that make it important.
Matching Established Perceptions
Adaptation means that it is based on an existing story, and for people who have already seen or read the source material, there will be certain levels of expectations that producers have to match. Otherwise, it could anger the fanbase the adaptation is trying to appeal to.
No explanation is needed to know how bad that can be. Even just the inaccuracies in physical appearance can dissuade fans from watching the film or series. Small differences can be overlooked such as eye color, provided that it has no significance to the story.
Some take the risk of not sticking to the established descriptions of events and characters and manage to pull it off, but it's a gamble. Some who have taken that gamble lost. Take M. Night Shyamalan's "The Last Airbender," which was regarded as white-washed and far from the original.
Producers and writers don't even need to copy the source material page by page or frame by frame, but they will need to stick to the original in the ways that matter, such as the character's personality and quirks, as well as other attributes that are repeatedly highlighted.
Avoiding Narrative Inconsistencies
A story will not get the attention it gets if the story is not compelling. Fans latch on to that and expect to feel the same kind of emotion in the adaptation. Changing parts of the story can not only lead to angry fans but could also cause the story to deviate from its main point.
For instance, a character might've had a cold disposition to make their story arc more meaningful by the end of it. Changing that could lessen the impact of the character's change or improvement, which in many ways is a waste of a good narrative.
It could also lead to plot holes that could ruin the story, or at the very least make fans uncomfortable for having unresolved story points. Staying on course would preserve the message or the theme that the original had.
Respecting the Source Material
The adaptation would not be possible without its original creators, which is why they deserve all the respect they can get from those who intend to remake or adapt their work. That includes avoiding major or minor changes when the creator might not be happy with them.
Sure, producers can do whatever they want once the rights to the story have been sold or licensed, but it's a matter of respect and integrity. There are situations where the original creators would collaborate with the producers to make sure that everything runs smoothly.
Not respecting the source material could anger the author or creator, and their fans could rally behind them. Take the "Percy Jackson and the Olympians" films. The source's author Rick Riordan practically condemned the film adaptation, and most, if not all fans of the books agree.
