Caravans and workshops should absolutely be able to provide a sizeable profit *with player input* into making them profitable, in the same way that fiefs should have ways to manage them for better returns. Both of the "trader systems" already have limits based on renown—which is a move that I like because it provides a long-term goal to reasonably acclimate to—and at least caravans have the additional drawback of removing a companion who could be fighting for your army (potentially adding perks.. once they function), building their own party's army, or governing your fiefs (currently not implemented well).
Ideally, your workshops and caravans should be able to work together to create serious profits, and bandits would be a more interactive aspect that players could work to suppress or make deals with to let their caravans thru. Similarly, being able to negotiate trade agreements and secure peace with other kingdoms are essential to making these game systems rewarding.