lol, looks absolutely ridiculous.
Why is it always assumed that there's some kind of supreme knowledge to unlock in our brains? Knowledge comes from experience, not from within.
If we used 100% of our brains (we actually do... just not for cognition, which is what I'm assuming they're talking about), people would still be just as lazy and dumb. Stupid movie premise.
There's actually a significant bit of research into the possibility that humans could be capable of things like telekinesis, eidetic memory, telepathy, ambidexterity and even things like pyrokinesis, immovability and incredible reflexes and reaction time. And there are scientific theories to support many of them, although some of them seem far fetched at a glance.
Most of what you see in movies is just these ideas pumped up on steroids and turned into science fiction premises. Akira, Scanners, Mobile Suit Gundam, etc., etc. etc. They don't all specifically state that these powers come from being able to use more of your brainpower, but many of them find their roots in the study of the human brain and how much of it is accessible through evolution, either forced or natural.
My problem with this particular interpretation is in that Lucy is shown having all of these amazing powers. So where's the tension? This is a Luc Besson movie, so I'm not seeing the potential for a person breaking down, being unable to function, going externally catatonic while being internally within their own world.
Doctor Manhattan is still the best representation of a super intelligent person just getting 'bigger' than the world they live in and growing more and more detached from humanity.
I'm interested in the pitfalls of all this psychic power rather than the power fantasy. Akira did a great job of showing that. The manga vastly better than the movie, but even the movie did a decent job of it.