Austin police to go knocking on doors of people with open wifi

Earlier this week, officers at the Austin Texas police department announced a plan to search out everyone running open wifi connections in town, in order to "warn" them about potential dangers of running an unprotected network. These dangers included exceeding the number of connections permitted by the ISP, or inadvertently allowing someone to piggyback on the wifi and conduct illegal operations. No word on whether it was legal to spy on residents in order to find out whether or not they had unsecured wifi networks.

I have to wonder: if it's not illegal to have an open wifi network, why is the police department wasting resources advising people on what is mostly a civil matter (violating the terms of agreement with an ISP, or copyright infringement)?

More important, what about the benefits of open wifi networks? The Electronic Frontier Foundation puts it best:

Missing from the [police department's action] is any recognition of potential benefits to be gained from publicly sharing one’s wireless access point. Lately, the virtues of contributing to any shared commons tends to be overshadowed by fears of bad actors (both real and imagined).