The reason I don't wish to speculate is because in the bigger picture, we know nothing. With respect to our fellow aviators the gadgets we get to play with are pretty impressive. Especially for en-route weather.
Which is why I'm not going to just agree with some ill-thought theory that the plane happened to fly into a CB. As with ALL flight accidents, there is a chain of events. What we will find out is that many things went wrong in order for this unfortunate event to occur, not just one thing.