All of them are worse than what they are replacing - more limited and more buggy. Sometimes because they are just new, sometimes because the authors don't know what they are doing. In any case, why switch?
Regarding "part of", there's a nice motte and bailey argument from systemd that they are absolutely not parts of it when talking to critics, but when it comes to shipping and using them, they are.
It was especially bad when udev "moved in with" systemd, there were promises to keep it working without systemd. These were swiftly broken. Assuming good faith from that crowd is a mistake.
Fortunately, there is a fork of udev that works without systemd, and you know what, it's not even a difficult one. So what were the strong technical reasons for adding the dependency?
I criticize systemd because for months my full time job was dealing with it. I suspect the minority of systemd haters are actually people like me, who actually had to do non-trivial things with it and realized how bad it is, if you actually have to do things with it.
Hating systemd is sort of a joke in certain Linux circles, where "Unix philosophy" and "minimalism" are tossed around. I don't really care about that discussion. Systemd is awful by any philosophy which aims to provide good software, for almost anything you can fill the word "good" with.