Who really needs systemd?
It may provide some features not previously existing, but it also breaks a lot of stuff that people "knew" were there.
Systemd is IMHO the best happing to Linux the +15 years I have been using it as my prime OS.
1. For the first time ever is there a coherent development of core Linux OS features. Take fx. "rootless X". It has been possible on Linux for a long time, but only by opening up massive security holes on multi-user systems. The solutions required cooperation between several kernel subsystem developers, X developers, and userland/systemd developers (session managing) to succeed. So secure rootless X is now possible on systemd Linux distros, simply because the systemd project could function as a developer nexus to coordinate and develop the needed features.
2. Since the entire commercial Linux segment and most other distros are becoming systemd driven, there now is a base compatibility layer on Linux for doing basic things like controlling networking, ntp, getting system information etc. Almost all new Desktop Environment development (KDE/GNOME/LXDE/XFCE) at the moment is based on systemd, simply because systemd offers powerful cross distro features that DE's can take advantage off.
3. It is now staggering easy for both distro maintainers, developers and end users to take advantage of advanced kernel features like CGROUP and Linux Capabilities. A simple edit in a standardized text config file can enable strong security features that prevent e.g., privilege escalation. The Linux kernel is full of advanced features that few take advantage of, simply because it often is hard to do with no basic framework outside the kernel to help the user. With systemd, it is now possible to expose many of these kernel features in an easy and consistent way.
4. systemd have actual end-to-end service supervision; systemd supervises all processes, and its watchdog can be made to supervise systemd itself, conditionally restarting it if it should hang.
5. Regarding "what people know"
Anybody being in the IT business for a decade or more have experienced how well known ways of doing things have disappeared. I knew how to optimize the DOS config.sys in order to have maximum available memory. Useful then, useless now. Overall a great improvement.
The reason why Linux is changing in the systemd direction, is simply because the way we do computing is changing; gone are the days with the OS running directly on metal with a few selected services, and the entire thing glued together with hand crafted scripts that were difficult for outsiders to understand.
These days it is all about virtualisation, OS containers, massive OS /node deployment with automatic processes, automatic zero config deployment, These days the SA's doesn't monitor a dozen processes on single server, but 10.000 or perhaps 100.000 processes on thousands of OS containers/servers etc.
systemd is simply brilliant at all this, and sysvinit is not.
Many reactionary retro grouches hates systemd because they now are forced to learn new stuff.
But this really is a wake up call for people; either they start learning systemd, or their Linux skills will not be in much demand in the future.