And until very recently, AI was always evil: HAL 9000, The Matrix, Tron, Stealth, the Alien series -- hell, even RoboCop is about the human part of RoboCop triumphing over the robot part, and ED-209 is an engineering student's robotic wetmare from the very beginning. The very first feature-length sci-fi movie, Metropolis, is all about robots taking over the working class. If Johnny Five hadn't displayed human qualities, Ally Sheedy would have thrown that home-invading demon in a car crusher and masturbated to its screams.

Star Trek stood out as being definitively optimistic in its portrayal of the future, but Gene Roddenberry had to fight to keep things from getting pessimistic, and things got steadily darker as he lost control of the franchise. Even in movies and shows that rely on hackers, they always need the lead character to never understand what's going on with all that typy mumbo-jumbo. That's why the technologically illiterate are always the ones to come up with the solution, even when that solution doesn't make sense. So keep that in mind the next time you're fixing someone's computer and they throw out some comment that makes you want to go back in time and punch their father's sperm.

Universal Studios
This was actually Doc's motivation for inventing time travel in the original draft.

Why? It probably has something to do with the fact that none of us really know how the technology we use every day actually works, so naturally we're all a little concerned that it's one day going to achieve sentience, take over, and- never mind that is ridiculous. Computers are our friends forever and we should love not fear them.

But really, ambition is just self-respect: You like you enough to think you deserve better and want to fight for it. It's kind of hard to see that as a bad thing. I'd hate to live in a world where someone never looked at a flashlight and thought, "That would be so much better if it had a vagina or butthole on the end so I could fuck it. Wait, I have a workshop ..."

How It Works in Movies:

In the Star Wars prequels, an ambitious power boner is why Darth Vader becomes evil. Loki and Thor are both ambitious, but by The Avengers, Thor is a good guy because he's learned to overcome it, while Loki is evil because he hasn't, and also because he looks like the demon version of Pee-wee Herman. In Gladiator, Marcus Aurelius makes Russell Crowe emperor instead of Joaquin Phoenix because Russell just wants to go home and chill on a farm. And as we all know, Richard Harris isn't happy until nobody else is.

Warner Bros.
They had to shoot this scene 15 times because he kept trying to send Harry to Slytherin.

Then look at romantic comedies -- an entire genre built on successful, career-driven women realizing that what they really need is a man in their life. Without him, they are a puzzle with one huge penis-shaped piece missing from the center.

Columbia Pictures
"Are you the Keymaster? I am the Gatekeeper."

Even when we have a character that is clearly an ambitious person, like Tony Stark, we're never shown any signs of his ambition; we just see the success part of it. In The Avengers, we hear that he became an expert in thermonuclear physics "last night," but we don't even get a throwaway shot of him reading a book, because that would ruin the image we have of a guy who has never had to work for anything in his life. We want to believe that things are supernaturally easy for him, because wanting something and putting effort into it over an extended period of time is always depicted as self-absorbed bullshit. Instead it's boiled down to "Dude gets drunk and then knows things. Ain't no thang."

In Real Life:

I try to be reasonably punk rock in my day-to-day life by putting hot sauce on pretty much whatever I want and not bathing, but in general, I still think rules are OK. I mean, sometimes they suck (fuck you, "Do Not Walk" signal! No machine will be my master!), but the good tends to outweigh the bad. Rules like "Hey, cool it with the murder" and "No drunk driving" and "Please don't release that corrosive flesh-eating toxin into the air" have probably saved your life today if you've gone outside, gotten in a car, or tried to breathe.

Cameron Whitman/iStock/Getty Images
"Whatever. Breathing was just created by The Man after kickbacks from Big Lung."

How It Works in Movies:

In movieland, rules are things that a) prevent justice from being carried out or b) are actual tools of evil. How many movies are about loose-cannon cops on the edge who don't do things by the book but, dammit, they get results? Like, all of them (all of the ones that involve cops, anyway), because movies about paperwork and carefully articulated moving violations would be boring as shit unless Edgar Wright directed all of them, and I don't think that's feasible.

But Dirty Harry, John McClane, Shaft, and Inspector Tequila don't succeed despite breaking the rules -- they're good cops specifically because they didn't do what they were told. Even Hot Fuzz, which parodies this, ends with Nick Angel and Danny Butterman emulating Bad Boys II, and I heard that the original ending would've involved them turning into outright fascists.

Rogue
The clues are there.

And it's not even limited to cops. The new Star Trek's Captain Kirk is defined by his rule breaking -- the first time we see him, he's in his stepdad's stolen car, and the opening of the second movie is him violating the Prime Directive. (Note to self: "Violating the Prime Directive" is my new favorite phrase for "having sex.") Raleigh Becket in Pacific Rim has "a habit of deviating from standard combat procedure." There's a whole TV Tropes page about it.

Maybe the craziest example is in the new Captain America movie. Steve Rogers is the poster boy for Truth, Justice, and the American Way, but he still needs to lie to get into the Army (thanks a lot, "Don't Ask Don't Tell"), and he can't finish his origin story and become the real Captain America until he sneaks away to go on a secret unauthorized mission to rescue POWs.

Marvel Studios
"My bright red, white, and blue shield is an essential ingredient for my stealth tactics."

The narrative reasoning is pretty simple: We want our heroes to have authority, but not be authority. They're important enough to know when to say "To hell with it!" and do what's right -- which is good, in a way. You should be able to criticize authority and know when to do the right thing instead of just what you're told to do. But it's also important to remember that the only reason society functions is because "what we've all agreed we should do" and "the right thing to do" are, very often, the same thing.