A critical design flaw that cant be changed easily.
Have you seen this article?
seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/
Can't argue with your post at all. The 737-Max 8 was just a step way too far, all because Boeing were trying to copy the Airbus philosophy of having commonality in the A320 family when the 737-Max 8 was clearly not the same plane as the classic 737 family.
You've forgotten to add that 3 (I think...?) of the 787's belonging to LOT are also parked because of engine issues. LOT are essentially having to lease planes at a high cost just to cover flights, which means they're going to sustain astronomic losses.