apparently they're waiting for an impending patch to the kernel to add lz4 "natively" so that they can just leverage that instead of their own version of lz4. Hopefully soon
what'd be really cool is if lz4-hc was supported as well as lz4, so when having mostly read and not written data can use lz4-hc, and when having write data can use lz4 normal.
although even lz4-hc as default on things like cheap ssds, usb sticks with fast reads and slow writes could be of benefit. although may need something slightly in between for slower computers. actually what could be cool is a background lz4 to lz4-hc thing that could be run to further compress files occassionally. (would probably speed up boots, and free up disk space, again more important on slow/cheap/small ssd's)