Christine Folch wonders in The Atlantic why fantasy and science-fiction are so popular in the West. Her explanation is applicable to steampunk.
Folch cites nineteenth-century German sociologist Max Weber, who argued that economic and political progress had “disenchanted” Western societies.
Weber posited that because of modern science, a rise in secularism, an impersonal market economy and government administered through bureaucracies rather than bonds of loyalty, Western societies perceived the world as knowably rational and systematic, leading to a widespread loss of a sense of wonder and magic. Because reality is composed of processes that can be identified with a powerful-enough microscope or calculated with a fast-enough computer, so Weber’s notion of disenchantment goes, there is no place for mystery.
But people like mystery. “And so we turn to science-fiction and fantasy in an attempt to reenchant the world.”
Similarly, steampunk harkens back to an era when adventure and wonder were, in our twenty-first century reimagination of it anyway, commonplace.