Trying to make complexity disappear by adding another layer is a classic error ...
... and that is what systemd appears to be trying to do, from my very limited reading.
From my perspective, there was a time, long ago, when a problem with booting or system configuration could be fixed by either editing a couple of conf files or in extreme cases editing or shuffling init scripts. That was the original unix model (mostly BSD?) The SysVInit model actually made things more complicated and difficult to figure out. Since then various attempts have been made to 'simplify' maintenance, but in order to support a GUI or even a Curses program, the configurations had to become more complicated, with configuration-modifying program configurations. It's been 10 or more years since setting up networks, especially dialup and later wifi, become so convoluted that it was impossible to figure out what was going wrong without climbing the learning curve of yet another system containing a dozen or two scripts/programs. Today it's basically impossible to get wifi running unless the fancy GUI NetworkManager magically happens to work. If it doesn't, one has to just resort to suspending, or in severe cases restarting, the laptop and hope that it discovers the wifi by itself.
As anyone who started out doing simple HTML with a few .SHTML or CGI scripts, then migrated to early PHP, then to CRMs and frameworks written in PHP, these are just layers of complexity that get harder and harder on which to achieve any level of expertise. No sane person could argue that working with Drupal is less difficult than writing native PHP. (Granted you get more built-in tools.)
Upstart was another attempt to 'simplify and automate' booting, but really just put another layer of crapola (scripts and configurations that interact in mysterious ways) between the system and the user/maintainer, and remove more information from visibility. So without delving into this issue myself, I'm becoming more and more likely to revert to an old-school distribution, and build it myself.
Bottom line analogy - I don't want to have to relearn how to drive yet again, as every piece of software seems to insist on moving all the knobs and wheels to different places and hook them up differently. Imagine if every two years your car's dashboard and engine controls were moved to random places, and you _had_ to update or else your car couldn't go on the freeway - that's what has been happening in IT for way too long. Funny thing - I could drive a 1946 Ford on the freeway today, and while it might not be as safe or as fast or as comfortable, it would work just fine.