One of the biggest issues with this problem is how complex the causation seems to be. There is no one single factor that a person can point to and say "This right here is how it happened". I suspect the solution will be equally complex.

In regards to 'how is it a problem?', it's hard to tell if it is or isn't, since in Silicon Valley, it has always been skewed towards these demographics, and as such, we don't really have anything to compare to. I have a hunch though that a lack of diversity in an environment so dependent on innovation will almost always be a net negative.