Yawn. The only surprise here is that they are not already doing it - if indeed that is the case.
If you really run an international criminal organisation or a worldwide terror web then you will either be ahead of this in someway or not bothered anyway. The real advantage to the government and it's various agencies is that it can be used to examine the intricacies of a persons life almost on a whim. Any 'fishing trip' is likely to turn something in a persons web browsing history, for example a visit to spunkytits.com, that need s a closer look 'just in case', and then everything is fair game.
Update: I have just found that spunkytits.com is a genuine web address and feel I need to investigate further.