People change as they age...  they don't necessarily "grow".  There are
huge numbers of people who did their most creative work early in life and
produced nothing of significance after age 30 or 35.

Gould is one of the few that could come up with something new upon
reexamination of Bach.  Not everybody agrees that the "new" version was
the better one.  There are 7 different recordings of Gould's Goldberg's,
most of them badly recorded, but the performances leave me with the belief
that only the famous two were special creative performances.  I personally
do not believe the later version has a better or "wiser" perspective.

In composition, I think there is just a much longer learning curve that
is also affected by the suggestions and criticisms of contemporaries...
as well as the wear and tear of life that results in some more powerful
works, as in the Beethoven late quartets.

Ray Bayles