One problem with «shinier, newer, better, securer systemd» is that many systemd opponents want something less shiny. And systemd is big and shiny enough that _even_ sysvinit is better.
Most arguments for sysvinit you list are, for example, arguments for s6: s6 is just a supervision suite with no other ambitions, PID 1 during the normal operation (not boot/shutdown) is s6-svscan — a 32 KiB executable, and the part that requires debugging — service launch scripts — can still be a shell script.
I am a systemd hater (at least for my patterns of desktop use — systemd can be mostly fine on some servers) and my opinion of systemd is that it is mediocre as a service management, has bad logging system bundled (is https://bugs.freedesktop.org/show_bug.cgi?id=69934#c7 fixed? can the systemd-bundled logging system give me the last 20 lines of the log without reading all 100 MiB of the log file — it previously could not?), and breaks my workflow hard (nothing similar to startx can be implemented by design http://lists.freedesktop.org/archives/systemd-devel/2012-Feb... for example), and systemd updates make systemd try to control more of the system which I explicitly do not want controlled automatically (I have a very handy binding for standby, and I do not want the notebook to suspend on lid close; I have multiple network configuration scripts for each of three typical locations and choose between them depending on whether I plan to move around more than transfer multiple-GiB files; killing all this autoconfig requires work).
I would probably use uselessd just to avoid bothering if NixOS shipped it instead of full systemd; it doesn't so it is more comfortable for me to use a NixPkgs-based system with init=/bin/sh and minimal hand-written init scripts than stock systemd. I was capable to use systemd almost fine until systemd has ensured that startx-like functionality is impossible to get.
Edit: a typo