[color_me_not]

> Romanization is for foreigners. Japanese people would read the original kana/kanji anyway

Assuming it is only used for reading purpose. It is actually also useful for typing in Japanese with a keyboard without kanas, though it is still mostly relevant for foreigners.

Side note: I personally like input systems that support both romanizations simultaneously, since there are shorter combinations in each one. For instance, "si" saves one letter compared to "shi", and "ju" is also easier to type compared to "zyu".