Unless you're intending to make the argumet that accessing those files is the same as you leaving all of your personal belongings on the street, I'm not seeing any differences.
> For example the police can search your belongings unless they're locked, then you need a warrant.
The police need a warrant, I [an individual] do not. By your argument, I can come to your house and go through all of your things just because you left the door unlocked.
> If you've got a service wide open on the internet with no security it shouldn't be a crime just because somebody found it.
I don't think anyone here is saying it is. The argument is it's illegal to search through the data made available by that service without permission.
> It's like an open door that throws a copy of it's contents at anyone that finds it.
It's really not. Here's an exercise: Name a protocol used on the Internet that does NOT make a distinction between connecting and the client requesting information.