In my opinion it's not a bad decision... honestly I made an account back in 2010 when Ayu started to use it and I loved to see what she shared with us but to me she used twitter too freely for a celebrity of her level and several time she had controversies with her twitter account ... there are lot of celebrities which don't use social networks by themself ! Therefore they are maintained away from hater, spammer and crazy fans ... maybe only share some pics of her and things about her music is the best choice ...she shouldn't feel the need to share more about her personal life !! Yes it's sad but it's for better imo