>your argument essentially hinges on the assumption that pulling hard back on the stick is a sufficient solution for all the problems that may happen with a plane with the exception of a fault with MCAS (the new system).

I don't read it that way. To me, it's specifically based on removal (without notice to pilots) of a function that would absolutely have terminated a trim runaway condition.

In other words, Boeing eliminated one well-known and trained-on trim runaway fix, and didn't tell the pilots. This is different from saying that stick pullback is a universal solution.