Habba, I think you're missing the point. Surely it's worrying in a sort of general way that huge amounts of personal data are being stored. You raise the rationalization, I think, that it's so huge that what are they going to do with it?
But what if YOU become a suspect.
Are you assuming you won't become a suspect because you don't fit some ethnic demographic? Because that makes you complicit in profiling, if that's the source of your comfort. And profiling is just stupid. I hear stupid people all the time saying, why should these poor old white ladies be subjected to searches at the airport when there are all these really obvious brown young men walking around without reproach? How hard could it be to find one 55 year old white lady who is in desperate need of money?
Are you assuming you won't become a suspect because you're a law-abiding citizen? How foolish. You have no idea what kind of activities would put you on a watch list. You could raise a flag for booking a one-way ticket. Or returning from holiday in a middle-eastern country and depositing leftover currency in your bank account. Or going to a protest (although I doubt your the type).
I'm actually shocked that there are people who aren't bothered by this.