To actually look at a user's data will require a warrant
..or a slow Friday afternoon fishing expedition. I can see it now:
'Hey, I have a list of websites here. Let's run through the 'metadata' and see who we can catch. All it takes is for Abbot or one of his creeps to make some bogus statement about how this crime or that murder could have been prevented if only our brave boys in blue could have got to the data quicker.
Cue the announcement of a centralised mirror where every ISP can send the data.
Only accessible to properly authorised people of course, like bored operatives or people showing off to their mates, or a cop looking for something to teach the bastard who bought the last doughnut in the shop a bloody good lesson.
Don't know about you, but I feel safer already.