>Of course it will be a securely guarded technology, so that it won't fall to hands of random strangers, malicious hackers, or burglars; only the law enforcement agencies would use it, and only for legitimate purposes! Honest.

Here lies the problem. You can't guarantee that. Law enforcement itself has criminals. In some countries law enforcement is even one of the largest collection of criminals. And then something like Trump happens. Do you really want to give such powers to people like Trump and it's followers, not to mention more malicious ones?

There is no way that this technology is only used for good.

And what comes on top, it doesn't stop crime, just it's modus operandi.

If they can't use their computer to handle certain data, they use hacked ones and hide it there. You know the trick how drug smugglers use the suitcases of tourists to smuggle their drugs?