Entirely a PR stunt. This is a move that is meant to show "unlike our competition, we won't just standby with standard procedures for launch console problems. We're better." It's probably also a call back to their red ring situation years ago trying to say that, this time, they're on top of things. Regardless, it's still poorly done. See, this isn't good for, say, if your console doesn't work at all, or really, if it has any other crippling issue than the fact that the disc drive may not work. It's only good
if you have a disc drive failure, as the intent is to keep you in the game with their return system that makes it so you don't even have to turn in your old system while waiting for the new one (since a broken disc drive makes your system essentially worthless for most purposes).
So, plus side:
+ You don't have to turn in your console before they send you a new one while getting a game to tide you over
Cons:
- It only covers a single problem of many that could occur
- It's an unnecessary PR stunt that is ridiculously see through and still manages to fail
Realistically, the fact that Microsoft feels it's necessary to try so hard is kind of sad. Last I checked, the majority don't expect compensation when they buy launch time hardware and they're part of the minority that got shafted by the luck of the draw.