^This.Effective place making comes from the details that support and build the intended place/experience. The subconcious is won by the the elements that together convince you without distracting you. The point of the bridge looking as it did was not to fit 'a 1920s bridge' - but to fit a specific bridge.. one with ties back to both the trolly line and Disney studios heritage itself. It's choice was not random.
You might as well put in the brooklyn bridge with your train of thought... 'its still a bridge'
The bridges of LA are a big part of what adds the "magic" or the "mystique" to the city, and by association, what Buena Vista Street is about. How many recognizable bridges are there? The 6th Street Bridge? The Hyperion Bridge? The Colorado Street Bridge? 4th Street? These are big, majestic pieces of art and influence to the city as a whole. They inspired songs (Under the Bridge by the Chili Peppers being a notable example), they're picked as movie sets (Drive, The Dark Knight Rises, Terminator 2) because of the unique, and all around cool feel they're able to add to a given scene.
They're a part of the history, just as much as Lincoln's looks.