I dislike many of those statements, because optimality is neither simple nor complex. And that's why I totally agree that it is difficult for a tune to appear simple, but recognizable.
Corrolar: software should be just as complex as the problem that it is trying to solve, and if the problem is difficult, the code will be difficult. Finding an optimal code might be more difficult than the problem that is supposed to be solve.
Yes, however, do you think that music should be beautiful? And is beauty easy, or hard, to apprehend? If your answers are 'yes' and 'easy' then I think you'll naturally appreciate simplicity or the emergence of simplicity from a complex background.
Corrolar: software should be just as complex as the problem that it is trying to solve, and if the problem is difficult, the code will be difficult. Finding an optimal code might be more difficult than the problem that is supposed to be solve.