In terms of privacy - my current traffic is monitored by my ISP (and data is sold). They say that this does even more but what - a lot of these systems actually encrypt and hide from ISP.
In that sense, the economics seem pretty comparable to ad support on the internet to me: By letting advertisers use your internet connection, processing power, screen space, and time, you get access to content that would otherwise be behind a paywall. And ads use up data caps and congest networks as well, in some cases even more so than the actual "pay"load!
I know that some people object to ads on the internet on the same grounds (usage of one's resources without compensation or consent), but this is a wholly different story from the liability issues that operating an open wi-fi hotspot can cause.
This stuff is designed for low power devices sending out a kb status update every few hours, otherwise they'd just put a normal wifi radio in it, and all the people here complaining that the Amazon devices they already put on their networks are now sending more data would just connect them to their wifi networks without an issue.