Campaigns would be good if the resources came back if you failed to wipe out the troops, or at least 50% of them, doing one can cost you a few elephants, then have to do it again without reward, so most people would just stop doing them, like if I have nothing to get why bother ?? but if resources filled up again for the next try then I would do them again and again until success, but then that can be abused for resources, so I really don't know, it's good return if you can win the first time, but lose and you will lose much more resources then gained