>>2943890It's childish because it's usually done by newish photographers having their first deep thoughtz about presentation. It's like grabbing your dad's empty briefcase and an old necktie and playing business man for the afternoon. You aren't actually doing any business, and white digital borders don't actually help with "neutrality" or "separation" or any of the other bogus justifications you see trotted out time after time.
And, full disclosure, they feel childish because I used them when I was a kid, way back in 1999. I used them, and I even had four or five photoshop droplets that would make different borders depending on my mood. I quickly outgrew them, as did the rest of the Internet design/photography community at the time, so to see them make a comeback is pretty funny.