Yes, it means having all of your data available for any criminal or civil court case. It means that any data breach will likely also include details about your life that you would like to remain private. Sure, it's not abused by the government right now but what happens in a regime change? What if that regime hates black people or homosexuals or muslims? So yea, it means a bit more than being shown personalized ads. How'd that Ashley Madison leak go? How about the OPM hack? How about Equifax, where's my SSN at now? Who knows my credit score? Then it also goes to conversations that used to be private. Mark Zuckerberg started deleting all his old conversations on Facebook, but how many of our chats, blogs, conversations, and comments are going to linger on?
"Sure, it's not abused by the government right now" - actually I think it has been by many governments many times.
There has been some push back on occasion, (facebook wanting to withhold data against the NY AG looking for insurance fraudsters with pm data?) and in some cases the gov has backed off, a few times the courts made them back off some (the dreamhost site visitors data requests from sessions and co?) -
There are many more examples, however I agree with your comment and I think that in general most people are unaware of massive gov overreach with data requests at the moment, so most would say the data is not being grossly over used / abused by (the US) gov right now.
However that could change quickly, just as the cambridge analytica made people start to question some things with private companies use / abuse.
