Number 1, why the hell are you complaining here, Sony won't read your complaint here, go shove it at them not us.
Number 2. Actually that requires hardware support which may not be implemented on the device. LED brightness cannot actually be safely controlled via normal means, they have a fixed voltage they must run at for prolonged life and as such it is impractical to use voltage manipulation to alter the brightness, current draws are always fixed for a given voltage so thats out the window too. The correct method is PWM, effectively to achieve a half brightness with PWM, it repeatedly turns the LED on or off hundreds of times per second, the human eye cant catch the on/off transition and just sees it as a dimly lit LED, however this requires hardware support and device drivers or device drivers which consume a nasty amount of CPU time to emulate PWM. It is most likely that they dont have it rigged up to PWM.