What I read was that these planes have larger, more efficient engines. This meant that they had to be mounted somewhat differently on the wing, and this affected the plane's center of gravity. This caused the nose to have a tendency to point up, and required software to keep it safe.
I do really think this is probably a software issue. Not enough pilots from the sounds of it got enough training, and when things go wrong, they didn't know how to fix it. The plane is only able to react based on what it knows, and when a sensor goes bad, its getting bad info and making bad decisions based on that info. In an article, other pilots said they could only recover once autopilot was fully turned off, but these poor guys in the recent crash probably had no time since it was just after take-off.