And that's the rub - it was initially advertised as a quick way to start the system, which is a simple enough concept to understand, then changed its scope to manage the entire system/service land.
It also ended up being tightly coupled, with poorly documented APIs and major bugs, which drew the ire of some longer-term professionals.
I don't think the idea systemd shim layer of services is necessarily bad, but I do think that having its design and implementation centralized within Red Hat isn't the best ; it would be nice if there was a complement to the Linux foundation doing its development, as having the process be managed by someone as competent as respected as Linus would go a long way into quieting the storm around it.