The question of why Logan became the third comic book movie (as in, film based off a comic) in recent memory to be nominated for an Academy Award for Best Adapted Screenplay initially provokes a cynical response. It was nominated, so this line of thinking goes, because it subtextually and textually takes the piss out of the superhero genre while being itself essentially a Western in the mold of Unforgiven or The Searchers. While still a "genre film," it's a genre that the large body of mostly old, mostly male, mostly white, mostly straight men who make up the Academy of Motion Picture Arts & Science's voting body grew up on and have extreme respect for.
Logan's metatextual piss-taking of superheroes is present throughout but it's best demonstrated by the hotel room scene where Logan (Hugh Jackman) angrily confronts Laura (Dafne Keen) and Charles Xavier (Patrick Stewart) over the fact that "Eden," the North Dakota-located paradise and mutant refuge that Laura's late mother figure/nurse/rescuer Gabriela (Elizabeth Rodriguez) begged Logan to take his cloned child to, turns out to have been lifted from the pages of an old X-Men comic. (Created especially for the film by Dan Panosian and Joe Quesada.)
"Maybe a quarter of it happened, but not like this," Logan groused. "You do know they're all bullshit, right? Maybe a quarter of it happened, and not like this. In the real world, people die, and no self-promoting asshole in a...leotard can stop this...This is ice cream for bedwetters," he snarls. When you hear that line, it's not hard to imagine an elderly Oscar voter chuffing in agreement. Why YES, there are too many of these damned superhero movies, this hypothetical voter might think. Why, back in my day, we only had them in movie serials. And otherwise, it was nothing but Westerns and crime pictures all the day long!
The subtextual teardown of superheroes -- and specifically, other superhero movies -- is a bit harder to immediately grasp, but is an undercurrent from the very beginning of the film. Remember, this movie begins with Logan waking up in his backseat to an attempted carjacking and the title appears right as Logan is lying prone in the dirt, having been knocked down by a gangster.
"Yeah, ya see that?" you can imagine the movie saying. "That's what I think of your precious Wolverine! He's old and weak now. Deal with it, nerd!"
But such a cynical response -- it dresses down superheroes, so of course a voting body full of old people is gonna nominate it -- is, while understandable, also pretty unfair, both to the film and screenwriters James Mangold (who also directed the film), Michael Green and Scott Frank. Instead, it's pretty obvious why Logan earned its nomination. In the end, it's a powerful piece of writing that does what it sets out to do; namely, provide a swan song for Hugh Jackman's 17 years as Wolverine. More than that, it's also a brilliantly bleak, but not hopeless, meditation on aging, regrets and coming to terms with your actions.