Be responsible netizens, says Germany.

If you live in Germany, then you'd better put a password on your wireless router now.
A German court ruled that those with internet connections hooked up to a wireless access point must put a password to secure it or else face a fine of up to 100 euro, or around $126.
"Private users are obligated to check whether their wireless connection is adequately secured to the danger of unauthorized third parties abusing it to commit copyright violation," the court said, according to the AP.
This ruling came after a musician sued an internet user whose open wireless connection was used to illegally download music over a file sharing network.

The courts, however, will not be holding users responsible for what happens over their wireless network. So, it seems that making a password mandatory is the sensible measure of legal responsibility to put on internet subscribers.

So open hotspots do not exist in Germany then?

Google admits wi-fi data collection blunder
Google has admitted that for the past three years it has wrongly collected information people have sent over unencrypted wi-fi networks.

http://news.bbc.co.uk/1/hi/technology/8684110.stm
Here is another reason

Dr Ian Brown, an expert on privacy and cyber security at the Oxford Internet Institute, told BBC News the wi-fi data collection was part of an idea to accurately map a user's location on Google Map and Street View.

"The idea was to use to the different signals and strengths from wi-fi and phones to position a users - think of it as a sort of GPS.