Here's the link: http://www.psxextreme.com/psp-news/2193.html
The 3DS' battery life is estimated at 3-5 hours when you have the 3D fully on. It has much better battery life when you turn the 3D off, as well as a performance boost with some games.
It is being used either way. You just get different benefits and there will always be some people who the 3D just isn't for.