Are we too protective of children today? Should we let them take more risks?

At a time when, by many measures, children are safer than ever before, parents have been investigated or even arrested for allowing children to play or roam outside unsupervised, and playgrounds have been padded, softened, and stripped of all but the gentlest and safest of equipment.

Driven partly by litigation concerns and partly by scare-mongering media, grownups have sought to minimize or eliminate every conceivable risk in children’s lives. But children need to face risk, experts say, in order to learn to understand it, manage it, and develop self-confidence.

Risk doesn’t have to be actual to be beneficial on some level. Vicariously going with the characters of a book or a movie through dangerous or stressful situations can help both children and adults develop emotional resilience.

This is part of the appeal of scary movies, and it’s something children especially need — in appropriate doses, of course, meaning enough to be stressful, but without traumatizing them. (For more on this argument, see Gerard Jones’ “Killing Monsters: Why Children Need Fantasy, Super Heroes, and Make-Believe Violence.”)

Which brings me to the family films of Brad Bird, whose “Tomorrowland” opens in theaters this weekend.

Few filmmakers working in Hollywood today enjoy so sterling a reputation as Bird. Although “Tomorrowland” is only his fifth feature film, and only his second in live action, his achievements in his first four films are extraordinary.

Bird’s two Pixar films, “The Incredibles” (2005) and “Ratatouille” (2007), are standouts even by the rarefied standards of that amazing studio, establishing Bird as one of the most notable makers of family entertainment today.

His feature debut, “The Iron Giant” (1999), is much beloved, among other things, as a striking departure from the Disney formula during Disney’s most successful decade: a non-musical with a 20th-century American setting, no cute animal sidekicks, and a non-romantic central relationship.

His last film, “Mission: Impossible – Ghost Protocol” (2011), isn’t a family film, and lacks the thematic depth of his other films (not incidentally, it’s his only film to date on which he is not credited as a writer). Still, it showcases Bird’s flair for crafting standout set pieces and for blending action and humor.

Except for “Ghost Protocol,” all of his films to date (including “Tomorrowland”) are PG or G-rated family films, and share a fundamentally positive, hopeful outlook. Yet they also share a bracing, almost dangerous spirit; they are less like the padded playgrounds today’s children play on than the ones their parents grew up with.

Young Hogarth, the protagonist of “The Iron Giant,” lives in 1950s New England during the Cold War — a time, the film reminds us, when schoolchildren were shown instructional videos about what to do in case of a nuclear attack.

The story includes, among other things, a train derailment, a terrifying sequence in which Hogarth’s beloved robotic friend involuntarily transforms into a weapon of mass destruction and nearly kills him, and a nuclear missile attack that nearly obliterates Hogarth’s town.

Perhaps even more unsettlingly, there is an adult authority figure — a government agent — who menaces Hogarth behind the back of his unsuspecting mother, even threatening to have Hogarth removed from his mother’s custody.

“The Incredibles” empowers its child characters with literal superpowers, leveling the playing field somewhat between them and the adult villain, Syndrome, a technocrat with no innate powers. However, as Violet and Dash lack their parents’ experience using their powers in the field, they’re as terrified as any child would be when Syndrome tries to kill them and their mother, Elastigirl.

Highlighting the film’s emotional realism, Elastigirl asks her offspring: “Remember the bad guys on the shows you used to watch on Saturday mornings?” They nod, smiling, but the smiles vanish when she adds: “Well, these guys aren’t like those guys. They won’t exercise restraint because you’re children. They will kill you if they get the chance. Do not give them that chance.”

“Ratatouille” opens with a not very disturbing sequence of cartoony violence, with an elderly woman wielding a rifle against a clan of rats infesting her house, including the protagonist Remy. The film’s darkest point, though, comes when Remy’s father attempts to force him to face the harsh truth of relations between humans and rats.

Leading him through the darkened streets of Paris, Remy’s dad confronts him with a pest-control shop with a plate-glass window display featuring row upon row of dead rats hanging from display traps. However, Remy won’t be deterred from pursuing his dream of working alongside humans in the human world.

That willingness to face a harsh reality, but in a fundamentally optimistic, hopeful context, is typical of Bird’s family films, and it’s just one thing that makes “The Iron Giant,” “The Incredibles,” and “Ratatouille” so special.

P.S. Ironically, with respect to danger, the PG-13 “Mission: Impossible – Ghost Protocol” gets off to a wobbly start: An opening set piece involving an impossibly precise escape from a rooftop suggests that we’re watching a live-action cartoon in which essentially anything goes, thereby lowering the stakes and the excitement level.

About a half-hour later, though, there’s a tense escape from a hospital in which Tom Cruise’s Ethan Hunt desperately contemplates a risky stunt he doesn’t quite dare to try — to the incredulous amusement of a watching antagonist. The other agent is astonished, however, when Hunt impulsively tries an even gutsier move, not quite nailing the landing and injuring himself in the process.

Suddenly we’re in a non-bubble-wrapped world … and the movie kicks up a notch.