Bullets and bracelets didn't power scale through time as other Silver Age heroes' powers did. In 1945, blocking bullets with bracelets was probably extremely cool; I don't know, I wasn't around back then. By 1965, guns weren't nearly as ominous as the sci-fi and fantasy threats heroes were facing.
Decades later, creators were faced with a dilemma: if a thug tried to shoot WW or hit her with a pointy object, how should she address it? All of the other flying bricks just had to stand their ground and let the objects bounce off them harmlessly, but WW? You either observe the tradition or make her generic. I don't think either answer is completely correct without adding a lot of context to it, e.g. she does the brick routine unless the object can hurt the most powerful beings, she uses her bracelets because she can or she wants to prevent richocheting that could hurt bystanders, etc. I think the movie looked cooler for having the bullet-blocking scenes, but that makes her seem less powerful than other flying bricks.
In short, it's a strange Catch-22. It's like the stuff that looks cooler makes her seem less powerful, and the only way to manage both is if you do a lot of explaining, which could bog down a TV show or movie.