"We ought to do good to others as simply as a horse runs, or a bee makes honey, or a vine bears grapes season after season without thinking of the grapes it has borne." — Marcus Aurelius, Meditations
The answer to 'why work hard?', 'why strive for perfection?', 'why care about craft?' does not need to be more complicated than 'duty'. When was the last time you saw a bee be lazy? Humans were made to make.