You make good arguments and if I could, I'd mod you up even though I don't agree with you. One of the reasons that linux has been popular as a server OS is that you could easily distill it down to just the parts you needed. If you didn't like a particular component you could swap it out with a component more to your liking or even write a replacement. From a security standpoint, you were presenting a smaller attack surface by running a small number of heterogeneous components from different sources. From a maintainability standpoint you could easily read and understand the impact that updates might have. Sure, there were kludges and hacks and, if you wanted to argue that X-Windows is the most prolific kludge in the history of computing, I probably wouldn't argue with you.
The small, modular, "do what I want" nature of linux is basically the thing that makes linux, linux. If you wanted an opaque box that included everything but the kitchen sink, you could just use Windows. And that's what people hate about systemd: It's starting a trend to make linux more Windows-like and that is rightfully seen as a horrible direction to take things.
You might argue that I'm making an ideological argument but, linux has gained its popularity from sysadmins; not from developers or desktop users. Sysadmins value stability, simplicity and the ability to understand the system they are running. Systemd effectively removes all those features from the OS. Yes, it might make it easier for desktop environment developers to implement certain features but, the number of people that use linux as a desktop environment is laughably small compared to the number of servers running linux. So, basically, systemd is undermining the primary use-case of linux to appeal to an unlikely to ever grow user base (desktop users). Which is made even more bizarre in that it's primary developed by Red Hat: Practically the champion of linux as a mainstream server OS.
Basically, linux users don't want the OS to become a giant opaque monstrosity that can be prodded and observed but never really understood (like Windows).