I think you can infer that they're trying to address some of the issues with the keyboard, specifically the dust-breaks-everything bit. There was an ifixit article[0] posted a day or two ago touching on some of those points. The tl;dr there is that the quiet aspect is a result of what looks like a fix for the high failure rate of the keys. They can't admit that it's an issue, likely for legal reasons.

[0]: https://ifixit.org/blog/10279/apple-macbook-keyboard-cover-u...