NNs aren't smarter than us, and thus won't magically uncover something that you haven't already figured out. But you can use Machine Learning to uncover patterns if you tell it what to look for. They're really good for testing stuff out in mass amounts that would otherwise take us months / years to do. Use ML / NN to extract rule sets for building a system, not to trade the system itself.
Exactly. Machine Learning is a great toolset to do stuff faster and discover faster algo when it comes to computers. Like if the trader knows what to look for ( the patterns ) then machine learning can help find it in a less amount of time than it would take for a normal scanning methods. Excellent post btw.