I am another retired heavvies driver (B744) who is at a loss why an experienced crew (almost all had lots of GA/gliding experience, so a good understanding of basics like stall/stick&rudder flying) looses it almost right from the beginning.
The next moment (I mentioned it before) the PF gets more or less frozen in his actions, a well trained and rehearsed crew concept breaks down in a snap.
Basic instinct takes over, like pulling the stick to its aft limit, to get away from approaching death. How many of us had this horrible experience and lives to tell? Bet that almost all crashes, with aircrews in their last seconds, will have the stick or Yoke pulled to its aft limit. Stalled or not.
As a result of his actions the plane did not at all react to his input, worse, the thing just would not go up and kept descending, not even with full power and a high nose UP. That further made him loose the situation.
I have, like no one else, a single answer to this crash, it will take for years to study it. The industry as a whole will have to learn from this so that all those who died did not in vain.
For the choice of the routeing: I have flown the stretch many times. I remember only seeing once or twice some dim lights of Ferdinando de Noronha, a small island there. For the rest it is pitch black outside. No lighted fishery fleets(like the Indian Ocean), or even better lighted oil platforms like in the Gulf of Mexico. This would never had happened over lighted areas like Europe, although I did not read IF they got ever into (nightly) VMC conditions. But if so, with a sinkrate of 7000'/min, it was only seconds before impact. The agony suffered in the back by all who realised more or less that the situation was getting out of hand must have been terrible.
The ITF (ITCZ) itself is not so much a big deal, thousands of crews are passing it every day, be it east of Brasil, or right over Africa, or throughout Asia.
In the planning phase it is difficult to find the "best" route, as CB activity develops, changes and dies within hours. For crews a challenge to find routes through passes. That indeed needs experience up front, there are sooo many variables, there is no golden rule how to pass or cross a system like that.
Circumnavigating comparable systems when over US territory is much easier for pilots, as the ATC system is way more effective in rerouteing traffic, away from cells or reported turbulent areas. Once I got rerouted as early as with our landfall over NY, due to a quick developing system on our planned route to MEX, hours later.
On transatlantic routes the pilots are much more on their own in figuring out to avoid bad areas.
Maybe less experienced crews tend to remain too close to the "magnetic" magenta line, I went off track 150 miles if needed to.
But now I enter the balcony level of Statler and Waldorf. I for one have never had to deal with situations like this or Sully's and I am glad I never had to proof how I would have reacted.