I'm inclined to believe that things like this could just be an alternative to ads. Ads take up CPU, battery life and bandwidth too (although a relatively small amount compared to coin mining). Alternative income source, I guess.
Providing a user with means to throttle or govern the mining seems appropriate even if not explicit. If I am trying to use my device put the virtual mining crew on break and dont check back for at least 20 minutes.
Secondly, exclusive mining rights. Only one app per device, but each developer can ask for a share of the haul. Having more mining apps competing for time will work in no ones favor. As the device owner I should inherently be entitled to a significant share.
An auditible mining client would be valuable. I could certainly see this as something that could eventually fit neatly somewhere between an optional and encouraged part of an AOSP deployment.