This is still a problem even if the Störerhaftung (WIFI-owner being liable for misuse) is removed: When the police comes looking for someone distributing CP, they go by the IP address and take everything that remotely looks like a computer for forensic examination.

So, having an open WIFI is like painting a huge target on your back, albeit a somewhat smaller one when media companies are removed from the list of potential trouble makers.

(See also: http://www.lawblog.de/index.php/archives/2016/05/12/dein-wla... (in German), for a defense lawyer's perspective)