the japanese have to use their phonetic language to type, a keyboard cant house all the required characters
further, this so called advantage is NOT specific to your language paradigm. For exmaple, many French and Spanish words are similar if not identicle, this is not cause by the way the language works but by the evolution of neighboring cultures. What our phonetic languages CAN do that yours cant is READ the other's language, though some words might be different, all sounds are the same.