I'm not sure I'd go as far as to say this Hammer works better than the comic Justin Hammer. I quite like him as a character, too. However, I think he worked better in the context of this Iron Man world than the comic Hammer does. The old CEO version is basically Stane, only without an armored suit. That can work in the comics, as you need a wide variety of villains and sometimes you'll have foes that are somewhat similar or made to replace other villains or become obsolete or die. But in films, you need to differentiate the villains from one another because there are less films, so overlap becomes a problem. The changes made to Hammer made him a distinct character, as well as staying true to the corporate aspects that are important to the IM series.