This is a disingenuous presentation, though I would not expect any different from a systemd proponent, or opponent, for that matter. I wrote about the follies of systemd debates here:
http://uselessd.darknedgy.net/ProSystemdAntiSystemd/The speed benefits come at the trade-off of integration complexity potentially diminishing them: http://freedesktop.org/wiki/Software/systemd/Optimizations/
Whether or not it is easier to maintain cannot really be objectively gauged. As for declarative configuration, I will grant that. systemd is not the first to do this on Linux, though. eINIT was, though it used XML as its configuration language (similar to launchd and SMF in fact, though not as verbose). eINIT also had the benefit of a modular plugin-based architecture, a property also shared by finit and initng.
Change does not imply progress. This should go without saying.
No, a lot of objectors simply come from having different opinions on process management and general software architectures. That said, there is a contingent who did approve of the old approaches, yes. I dislike sysvinit, but I can understand them. Serial execution with a concretely defined boot sequence that is easy to reason about can be a benefit to some. In contrast, the systemd approach eschews any definition of "boot process" or "boot sequence" that can be specifically intervened in by order, instead taking the philosophy that specifying a unit's dependencies and relative order to a target/synchronization point is enough, the rest being handled by internal transaction and job semantics.
systemd most certainly is monolithic. It is also modular, but to a partial extent. System generators and various auxiliaries (journald, but also some of the more minor tooling) cannot be disabled at build time. Certain things like Plymouth communication are also explicitly done at runtime.
launchd as a whole is still a much smaller system than systemd, at the end of the day. This is because launchd has a concretely defined purpose. systemd has little in the way of that other than vague descriptions that ultimately amount to being "as much as possible between the kernel and base libs+utils".