The sheer volume can create a needle-in-a-haystack situation for the watchers. The FBI has complained about having to search through a lot of calls to order pizzas etc. However, as you point out, software refinements continue to make the process easier. Maybe the worst potential consequence for most of us will be a bombardment of targeted ads. But maybe not.
As I said, my concern is the potential for selective use of information to punish people who upset the status quo... We all do things which could, if desired, be exaggerated through media exposure or otherwise into annoying, or reputation-destroying, career-endangering publicity. While I have no direct evidence to support it I can't help but believe that, for instance, Elliot Spitzer's behavior was known and kept in abeyance until he started actively warning about the financial shenanigans that were causing the disaster-to-come with the economy.
J. Edgar Hoover was well-known for keeping "gotcha" files on people for potential abuse in selective enforcement.
I believe that well-connected corporate interests have far too much control over the political process (as is amply demonstrated by the current inability of the process to protect some semblance of a public interest from the predatory greed of the financial, pharma, insurance, and other sectors). Especially now that the Supreme Court has ruled that corporations can spend as much as they want in the political arena, those politicians who are courageous enough to oppose special interests could be in for a very hard time. This could happen at a local level too as angry, frustrated citizens speak out against perceived harm to our interests. Although it is, of course, our right to petition for redress of grievances, the potential for misuse of personal information to besmirch someone's character might create a chilling effect against exercising this right for many who might consider it. The way things have trended, how unlikely would it really be that in the near future an attempt could be made to equate civil disobedience with terrorism. It's a matter of degree, and the political world generally doesn't "do nuance".
Maybe this is a paranoid view. Maybe not. I would just say that there's a tipping point somewhere, past which we should be wary of blindly venturing.
:kaffeetrinker_2: Rick