It is also significant, of course, that Smith is readily cast in roles that are not colour-specific. At 30, he's turning into the hero who most reflects the all-American idealised identity; it's no coincidence that he's had a run of films, from Men in Black to next summer's release, The Wild, Wild West, a spin-off of the Seventies TV series that is scheduled for release on 4 July. He says he can find the joke both black and white audiences will find funny - albeit not necessarily for the same reason.
He has also said that being black is in fact an asset in Hollywood today. "Once you've broken through the first slight block, you're a fixture in Hollywood. For myself, Denzel [Washington], Eddie Murphy, Larry Fishburne, our position is a lot more solid because there are so few of us. More solid than Matthew McConaughey or Chris O'Donnell, or even Leonardo DiCaprio. Because there's a thousand guys sitting there waiting for Leo to turn down a good piece of work. Also, with actors of ethnicity, there's an entire community of people willing you to succeed."
But does Smith really need moral support? He grew up in the middle- class suburbia of West Philadelphia, the son of a businessman who had come out of the army. One day, his father tore the brick off the front of the family's huge icehouse and told 12-year-old Will and his younger brother, Harry, that they had to rebuild it. Six months later, when the sons had finished, their father said to them: "Now don't ever tell me there's nothing you can't do." It worked. Smith still talks of his career in terms of careful construction. "My ace in the hole is my dangerously obsessive drive," he told American Premiere recently.
"He's been a success at everything he's done, from the time he was 15 years old," Bruckheimer says. "He's tall, he's handsome; he's at ease with himself and effortless in manner." It's the picture, in some ways, of a bland man. But bland isn't bad, necessarily. Tom Hanks once told me the secret of his success: "I don't threaten any man's sense of virility, or any woman's sense of security or decorum." The same could be said of Smith - and it's a surprisingly versatile quality. In Enemy of the State, he is the hero to Jon Voight's baddie. But: "The thing about Jon Voight is that he's really the sweetest guy. If he rang your doorbell and said his car had broken down, you wouldn't think twice about letting him in. I think I have that same sort of energy."
Smith started early in the music clubs, turning out rap that was edgy enough to be real, but safe enough to play in Peoria. At 18, he was rich and on the road, and though he didn't do drugs, the people he was around weren't exactly squeaky clean. By the time he was 20, though, he was through all that: "ready to settle down and have a family".
He was 21 when he took his rap character, the Fresh Prince, into the network TV sitcom Fresh Prince of Bel Air. Music videos apart, he had never acted, but the producer Quincy Jones persuaded NBC that he could do it. Smith, meanwhile, set about convincing himself.
He took acting lessons and studied tapes of other actors. His first film role was a small part in Where the Day Takes You, a 1992 film about LA street kids. His first important one was as the gay conman in Six Degrees of Separation, a role so unlikely that he reckoned it wouldn't matter if he failed. Needless to say, he didn't - he lists it as his only real acting credential pre-Enemy - but he also took flak for refusing to kiss another male actor on the mouth. Not a mistake he would make today.
His box office breakthrough was Bad Boys, the summer action hit of 1995. He always reckoned the way to be the greatest movie star ever "would be to combine Eddie Murphy, Tom Hanks and Arnold Schwarzenegger", he told Premiere. He'd done comedy; he'd now done action. He'd always, like Hanks, been "the regular guy". What was missing was the pure acting. That's why he took Enemy.
"When I came off Independence Day on to Men in Black, I don't think people had any doubt I could fight aliens. But Enemy of the State is more of an acting role. Any time you're in a film with people who have `Academy Award winning actor' before their name, it gives you the chills. But once you dive into the scenes, you find it lifts you."
He may - and it would be an important rite of passage - be about to play an African-American hero, Muhammad Ali. "We met a few months ago, and he said, `You're almost pretty enough to play me'."
But he still says that "music is the most personal thing - it's about me. As an actor you're more a tool for a director. It's about someone else's dream." Living outside LA with his actress wife, Jada Pinkett, baby Jaden, and Trey (his five-year-old son by a first marriage to Sheree Zampino), he has his own recording studio in the house - along with his own golf course, and all the appartus needed to ensure star privacy.
"There are things I have to defend myself against. The other day someone set a camera up in the bushes at my house. I have to have someone check the phones. But in LA, for the most part, you can hang out. If I go into Tower Records, well, Arnold Schwarzenegger just left." But the fact that his wife also has a public identity compounds their visibility.
"Like they say, the sum is greater than the parts and it often feels like there are more than two people famous in our house. One plus one equals five... People want the pictures that much more. It must have been the same with Bruce and Demi." The comparison is not unreasonable, really.
Ask about his future plans and you get a joke for an answer. "Run for President - I think I'd win." It is a joke, presumably? He has a shopping list of possible future movies, including a remake of A Star is Born, with the roles reputedly changed so that he'd play what used to be the woman's part.
"We're talking to Whitney Houston about the film; as for the part, someone suggested that concept, but we don't quite know what all the ramifications would be. I think in the end you've got to go for the Kris Kristofferson role - the drunk, someone who's frivolously frittering their life away."
It certainly wouldn't be typecasting. Not by a long way.
Enemy of the State is released on 26 December