Arguments for keeping track of everything seem to revolve around preventing people from doing bad things. If the good guys of enforcement have access to all communications then they can prevent bad things from even landing on the radar. Looking at patterns, anomalies can be spotted and investigated. From the anomalies, bad people can be exposed.
Perfect people would manage this information tracking system so it would only be used for its intended purposes. Perfect people would make the perfect hardware and software setup so it can't be hacked. Perfect people would peruse the data looking for information without thinking of personal gain. Perfect people would take utmost care of the data so no outside person sees it. Perfect algorithms to sift through the data. Perfect data to identify the right person. Complete and utter perfection now and indefinitely into the future.
People aren't perfect. The world isn't split into good and evil. Good people win since the winners decide what is good -- play on history is written by the winners.
There's enough information floating on the Internet, that if someone were to capture it, for a single person they could determine income, circle of friends, health status/records, interests, means of expression, opinions, every purchase ever done, current location, affiliations, etc. A complete profile, perfect for nefarious purposes.
Now I get off my soap box. This is probably a repetition of what others said. I just needed to collect my thoughts a bit and reflect.
