You need to add a "never worried about the noise, zero replacements" entry
Quite a lot of recent discussions on this. Comes up once a week.
Short story: pot luck based on manufacturing tolerances, you could go through a million and still have it 'rattle' when you shake it around. Pro tip, don't shake it.
That's the reason why you'll hear "worrisome" stories about the number of replacements, it'll be like finding one with a space bar that doesn't slightly tilt when you touch one side.
Please notice that, this is the noise of a hard plastic light guide plate, which was incorrectly glued.
If it's normal, then why don't all of them make this noise?
If a moving part inside a MacBook is OK, than how many moving parts are acceptable? Up to a dozen if they do not cause trouble in the machine?
Anything that is so minor as to not be noticeable in normal use (ie shaking a laptop to listen for a rattle) and does not affect the use of the machine is acceptable that is why there are tolerances in QC or they would never send anything out.
Ok, then why they replace it?
Nothing has been incorrectly glued, I don't believe they are glued in at all.
I have never seen a MacBook Pro that didn't have the display rattle. The only time it is heard is if you shake the MBP side to side, which I can't imagine in everyday use why anyone would do that....
Something tells me that whatever makes this noise behind the display is supposed to be slightly loose....maybe....
But knowing how Apples not existent quality control could be a factor here, it might just be a defect.
All I know is I LOVE my new Kaby Lake MBP and won't be returning it for one that might not have the "rattle".