Let's also not forget that every example we see may not be representative of what was typical for a certain type of piece from a certain era. Quality and skill varied widely and many things were made roughly by amateurs.
Even in the golden past we imagine, some things are done out of laziness, lack of skill or as Brian points out, expediency. We probably see the better examples more often because they were more likely to survive but every chest is not a treasure of ideal craftsmanship.
-- Dan Rode
"We are what we repeatedly do. Excellence, then, is not an act, but a habit." - Aristotle