And yes I am pretty sure they should revert the kernel change. Departing needlessly from the option name the other file systems give this is already wrong. But breaking all current systemd versions on new kernels just for the fun of it is extra wrong.
Note that I actually do think it's ok if kernel folks break interfaces every now and then if done for a good reason and if userspace is prepared. But here neither is the case. And my main beef here is that they claim they wouldnt do it ever...
rysiek