I am surprised it takes this long to make someone accountable. But it is too little too late, though a step in the right direction. It is clear that this program was flawed right from the get go.
I don't think the individuals really matter that much here. The point to firing executives in charge of big failures is to incentivize the ones remaining to get their ships under control before another disaster. Clark clearly failed on that front, but again the 737 MAX program isn't the end of Boeing's problems.