C’mon, Lucy. It is 2014. Why is there a movie based on the old myth we only use 10% of our brain?

In the brain only 10% of the cells are neurons; the other 90% are glial cells or astrocytes.
This quote came from here:
http://theconversation.com/do-we-really-only-use-10-of-our-brain-30045
So in one sense the 10% is correct.

C’mon, Lucy. It is 2014