Tabletop role-playing games are an inherently creative hobby. Sure, an adventuring party could pick a rule book and a bunch of pre-made character sheets and follow the words as law, but no one actually does. D&D is about the adventures invented by the players and masters, but how can an on-screen adaptation capture that feeling?
Watching a movie, on the other hand, is a passive experience. One viewer might take something different away from the experience than another, but the experience is the same each time. Putting a collaborative storytelling improv game into the world of cinema changes things and some people are never going to be happy with the results.
The upcoming Dungeons & Dragons movie Honor Among Thieves is about a ragtag group of adventurers going on a quest to get a magic item and stop an evil wizard. It's about as bog-standard as one could get when it comes to plot hooks for D&D campaigns. If that's all the dungeon master has for the first session, they'll need to come up with some pretty impressive NPCs to keep things interesting. However, through the first couple of trailers, the film has demonstrated a very comedic tone. It's most reminiscent of Guardians of the Galaxy in a fantasy setting. The characters bounce off of each other well, their solutions to problems are often one part slapstick and one part action, both films are even led by a wisecracking Chris. Some fans consider that choice to be blasphemous. The books would rarely allow for a tone so whimsical.
The world of the Forgotten Realms as written isn't very funny. Those who don't actually play D&D may have happened upon the stories of R. A. Salvatore, who made the dark elf ranger Drizzt Do'Urden the best-known TTRPG character of all time. He's probably been eclipsed at this point by Vox Machina, but he was big in the 90s. Those stories occasionally feature a bit of humor, but they tend to be very self-serious dark fantasies. Fans who spent years reading about the legendary journeys of The Companions of the Hall probably weren't expecting a lot of snarky gags in a movie set in the Forgotten Realms. This movie doesn't seem to match the tone of those novels or the extremely serious world-building of the lore books. Instead, the film is based on the real-life experience of playing D&D.
D&D becomes an exercise in comedy far more often than it resembles anything out of a lore book. The experience is inherently personal, so maybe a lot of people enjoy humorless games full of deep lore, but the average adventuring party spends as much time laughing as they do rolling dice. This is borne out in the on-screen versions of the game throughout the ages. Actual play podcasts skew extremely heavily toward comedy, with big names like Dimension 20, The Adventure Zone, and Rude Tales of Magic staffed entirely by comedians. Even Critical Role, which frequently depicts some of the most moving fantasy storytelling of the modern era, just as frequently sends the cast and audience into fits of laughter. Rick and Morty co-creator Dan Harmon mined the concept of fantasy TTRPGs being hilarious for three seasons with his criminally underrated series Harmonquest. Most D&D-related media is comedic, but that isn't the real reason Honor Among Thieves went for a jokier tone.
Family-friendly action blockbusters are expected to have a fair amount of comedy throughout their script. The D&D movie wasn't going to be Game of Thrones, and it certainly wasn't going to be John Wick. It's aiming for something entirely different, and it's right to do so. Rather than feeling like an adaptation of the world the stories take place in, the film is meant to feel like an actual campaign on-screen. It's supposed to be funny, climactic, silly, and absurd. Fans can almost imagine the type of person who came up with each character before the first session. There's a real chance that the film ends with the big reveal that the events of the story have actually been the story of a TTRPG being played by the real main characters. The comedic tone is an important part of selling this film as an on-screen adaptation of the real D&D experience.
Capturing D&D as a hobby means depicting the epic dragon fights and the prolonged comedic digressions. It needs jokes just like it needs sword and sorcery action setpieces. The Forgotten Realms setting is just important as a venue for hilarious bits as it is a deep and textured world. Dungeons & Dragons: Honor Among Thieves is a simple adventure film that seems to accurately capture the basic experience of getting the party together and having an adventure. Whether the adventure is any good remains to be seen, but they set out with the right goal in mind.