The German government has stated that collecting connection information beyond 1 week is unreasonable and unjustified to fight crime and terrorism. If you have reasonable suspicion, convince a judge and get a warrant, then you can wiretap as you wish, and you have the recent history. If not, don't store the data.
The German government has a guideline for all IT projects promoting the principle of collecting the least data ("Datensparsamkeit" ~= "data frugality").
Data tends to be illegally used for other things then intended. And it is not effective. It costs the government and companies real money. And it costs people their privacy without seeing something in return besides promises.