wallybird7: The ITCZ is a well understood area, that routinely presents challenging weather conditions. However EVERY flight traveling North<>South in this region of the World will transit the ITCZ. So your question "why were they dispatched into a known line of thunderstorms?" is rather misrepresenting the situation. This area of weather is not a rare occurrence, more so a common situation, and in fact the conditions that night were NOT particularly severe, with the term being "moderate thunderstorms" being the one most often applied after skilled analysis.
There were many other flights that passed through the SAME weather system, however the majority applied some diversion to a much greater extent than anything AF447 attempted. THAT to me is the most problematical concern of mine - WHY didn't they divert around the system?