...And mostly, why is it unable to turn this backlight off?
Gaming Consoles (and Mobile Phones, PDA's and other handheld devices) are always backlighted nowadays. Older devices, such as the GameBoy Color I still have, do not need backlight. The great thing of those backlight-less devices is that you can play them while sitting outside in the sun or near another bright light source. But with backlighted devices, while being able to use the device in a completely dark room, you will see absolutely nothing while in a bright area.
Is there a technical reason for the need of backlight? Or is it just the new standard?