Most RPM-based distros (openSUSE included) tend to follow RH's direction, so that's not surprising. Besides, SUSE has always been enthusiastic about most desktop efforts.
Arch Linux have at least two systemd developers on their team (Tom Gundersen and Dave Reisner). In fact, it was tomegun who wrote the Arch migration rationale: https://bbs.archlinux.org/viewtopic.php?pid=1149530#p1149530, based on the usual fallacious arguments (http://judecnelson.blogspot.com/2014/09/systemd-biggest-fall...).
Also, distros have blindly went along with other bad ideas before. The most prominent examples were HALd and LSB-style initscripts.
In fact, I'm not sure why you're at all surprised. Large groups of people in real life have collectively made far, far more catastrophic decisions. Why would a bunch of distribution maintainers adopting a piece of software be so shocking?