Usefulness isn't really the issue here.
We could start a new policy of random searches of people's homes. Your name comes up, you get a visit at 3 am and the police search all through your house, look at your financial records, scan through your computer, take blood samples and hair samples, etc.
I'm sure such a policy would result in catching all kinds of criminals who would not otherwise be caught. By that standard, it would be a very "useful" policy.
I'd still oppose it, though, because I do not want to live in a society where the authorities can randomly search your home. If I have to tolerate a bit higher crime rate to live in a free society, so be it.
Good post. Unlike many, it sounds like you get it