Sandman is one of the books that people hold up to illustrate that comic books are more than man-boys with muscles who wear tights. This series follows the exploits of Morpheus, the tangible aspect of dreams, as he tries to maintain order in the realm of human subconscious. Since the series ended in the late '90s there have been rumblings about trying to adapt Sandman into a film, but none of those attempts ever come to fruition. This is likely because it’s a really stupid f*cking idea. The reasons not make a Sandman movie are numerous, and many of them have to do with how the character simply doesn’t translate to the screen.
Everything that Neil Gaiman needed to say in Sandman was done in the form in which he wanted it to exist. By the time he was in the middle of his run on the comic, Gaiman was a popular, respected author and television writer – if he wanted to bring Sandman to the big or small screen he could have done it. There are multiple adaptations of Gaiman’s work out there (most of which he’s adapted), so that must mean that he has no interest in taking Sandman beyond the format in which he intended it to be consumed. For more reasons as to why Neil Gaiman's Sandman shouldn't be a TV show, movie, miniseries, or anything else but a comic keep reading and don’t forget to backcomb your hair.
Sandman Isn't Even The Character's Name
Yes, this is a small point but it's going to cause a massive headache for many viewers if a Sandman movie ever goes into production. The main character of Neil Gaiman's Sandman is named Dream, although sometimes he's referred to as Morpheus. This is already way too confusing for your average movie goer that just wants to watch buildings 'splode while Robert Downey Jr. winks at the camera.
Most superhero films are titled after the main characters as a way to brand the heroes for merchandising and onscreen recognition. You know who Spider-Man is because J. Jonah Jameson is constantly saying, "That rotten Spider-Man delivered a Christmas ham to my bathroom!" That doesn't happen in Sandman.
Usually, a dream mole wearing glasses slinks into Dream's ballroom where Morpheus is brooding about something in a Cure t-shirt and says something like, "Your highness, the nightmare goblins have delivered Christmas hams to the bathrooms of everyone in France." So there's already a problem with knowing who's talking about what on screen.
Plus, you;d have to deal with the purists who constantly correct less-informed fans. Don't believe it? Try referring to Link as "Zelda" in front of a Nintendo fan.
The Main Characters Are All Abstract Theoretical Concepts
You know how in Spider-Man Peter Parker is a guy with the powers of a spider? Or how Captain America is a guy who loved his country so much that he grew muscles? Sandman isn't about a guy made of sand (although that does exist), he's essentially the concept of dreaming incarnate. The rest of the characters in his story - Death, Calliope, The Cuckoo, The Furies etc. - are all also concepts or a tangible version of something imaginary.
They don't actually interact with anyone until that person also enters into the realm of the imaginary. Do you see why this wouldn't work on film? Viewers would constantly be turning to their friends to say, "Okay, so Death can only be seen by people who are about to die, and she's really nice. Also she's not a she, per se, she's a non-corporeal being who takes on the guise of a goth girl because Neil Gaiman has a type." It would be madness in the theater. Sheer and utter chattering madness.
Dream Is Aggressively Unlikable
It's not like all protagonists have to be likable, Mad Men was an awesome show, but Dream is a serious bastard for most of the series. Not only does he lock up his only love in a bone prison, but he makes Shakespeare put on a personal show for him and a bunch of elves, he makes a guy turn into a bear, he refuses to allow his son to die (until he does), and he generally just sits around and broods while everyone else does the actual day-saving. Finally, the protagonist that audiences have been waiting for. He really is the hero we deserve.
There's Almost No Action
You know what comic book movie audiences love? Talking. They just eat up hour long conversations about the nature of the universe. Frankly, it's kind of scary how batsh*t they go for pseudo-intellectual mumbo jumbo mixed up with references to Shakespeare and witchcraft. Sandman is an excellent read, but the moment you put Dream on the screen while he's trying to decide who gets the key to Hell by having drawn out conversations with a variety of otherworldly deities, people are going to be put to sleep. Huh. Maybe that would kind of be on brand, actually.