I do not have much to say about the Yoshida Brothers. Only that they have made a welcome effort to make the shamisen cool, frenetic and contemporary.
Why have Japanese musicians have found it so hard to incorporate traditional instruments into modern musical composition? China's composers, both classical and contemporary, seem to have had fewer problems insinuating qiu and other traditional instruments into modern compositions—or in using the traditional instruments alone for performances. Part of the problem is that traditional Japanese string instruments are plucked rather than strummed or bowed. However, the technique aspect cannot be the whole of it, for Indian and Pakistani contemporary music is rich with plucked sounds.
Of course, it might take an age to undo the damage wreaked on the nation's musical senses by enka orchestration.
Moody lighting and young dudes can help bridge the gap, as one can see in June's song "Kodō" by the Yoshida Brothers, on YouTube here.