sysvinit is widely considered awful by most distro maintainers.
How do we know this? Well, because distro maintainers have been trying to get away from it for years. Even when everything was run from 'init' there have been multiple refactorings of /etc/*.d to try to produce a better start up environment.
At some point, some distributions, notably Ubuntu, switched to an initd replacement called Upstart. Because they were desperate to get away from sysvinit. ChromeOS, possibly the most widely used Desktop GNU/Linux distribution, was also an early adopter of Upstart. Again because it was considered better - more reliable, faster, etc - than horrible old init.
So why are they switching to systemd? Because systemd is considered better than Upstart (which in turn is considered better than sysvinit.) systemd has a better process model, and doesn't ignore required functionality (yes, the same program that configures devices at start up probably should configure USB devices that are plugged in dynamically, and the same processes that configure the network based upon what devices are plugged in at start up should probably configure the network based upon what devices become available later, etc. So yes, this supposed "monolithic" approach is basic common sense.)
Most of those complaining about systemd are actually fighting an argument they lost in 2006, when Upstart became part of Ubuntu 6.10. They've lost it not just in the GNU/Linux world, but also in, say, the Mac OS X world, where sysvinit was unceremoniously ejected back in 2005. Or the Solaris world. etc.
You know, I could understand this if we were actually losing anything by switching to systemd. The desire to remove X11 from *ix, for example, replacing it with a dumb graphics engine with a fraction of the functionality, I think is genuinely a tragedy. We'll lose much of what made *ix what it is if and when Wayland is adopted. But systemd doesn't remove anything. It's fast, efficient, and it fixes huge holes in GNU/Linux, problems we've been aware of since the mid-nineties but haven't had the spine to fix.
It's something to be welcomed.