Barkerville Historic Town is the reason the detour exists. The town grew after Billy Barker's gold strike and is now preserved as a broad living-history site, with restored streets, working displays, interpreters, shops, and stories from the many communities that made the Cariboo Gold Rush work.
Give it time. A quick walk down the main street misses the point; the pleasure is in ducking into buildings, catching demonstrations, and letting the scale of the place explain how sudden and intense the boom was.