I think there's a couple of aspects to this:
1. Why didn't they follow Boeing's instructions? They weren't willfully doing something stupid like aerobatics or low flying or anything. They were desperately trying to save their own lives and those of their passengers. I think it's safe to assume they did they best that they could. Clearly, from what they experienced they somehow decided that Boeing's instructions wouldn't work.
2. When people doing their best end up crashing, you have to look for systemic problems like inadequate training or inadequate instructions.
3. It's a standard tactic to where possible blame the pilots whenever there's a crash, because that exempts the airline and manufacturer and everyone else from damages. We only have to look at the Erebus crash to see the lengths that they will go to in falsely blaming the pilots. So any move to blame the pilots needs to be taken with a grain of salt.
4. It does seem to me that, if the aircraft was in fact airworthy and recoverable, then some intensive pilot training in the recovery procedure would have sufficed. Instead, we're seeing months of software updates and documentation reviews and so on. That says to me that it's not as straightforward as we're being led to believe.
I largely agree with what you say here. I have some comments which I'll address using the paragraph numbers you used.
- I'm not sure sure they decided Boeing's instructions didn't work but rather they didn't understand them correctly. I say this because the actions recorded on the FDR and CVR show the procedures were not followed correctly. Training? Language translation issues? Inadequate wording?
- Agreed, and this is one point I have made previously.
- Agreed, but the evidence so far shows some level error from the pilots in this case. Like all accidents there isn't one cause.
- I think there's two points here.
- I believe (I'm not alone on this) the aircraft was recoverable and better training which I believe will come, will mean in future this type of accident shouldn't happen.
- If the system can be improved then Boeing and the FAA would be remiss not to take action and make improvements, be it improvements to the documentation or the system itself or both.