Maybe both, more situational awareness training combined with design improvements are needed. At high altitude, it is crucial to distinguish between overspeed and stall. For stall condition, how about to show on PFD Red/Brown colors (instead Blue/Brown). Separation line to be at FPV (flight path vector) location, the red above with big text STALL on it.
However, stall recognition is only half of the puzzle, the second one is THS position awareness.
Off the top of my head: West Caribbean 708, Air Algerie 5017, Birgenair 301, XL888, AF447, ROT381 have two things in common
- THS NU
- pilot error (stalled the airplane)
...and a good candidate for Guinness book :
https://www.youtube.com/watch?v=FJViilcDTyw
(sadly pilot error again)