Maybe in the back of someone's mind, but the whole planning and processing for the fedora project is really transparent. Just head over to lists.fedoraproject.org -- its all there. Crazy hard to find anything useful due to the sheer volume of it.
Here's the IRC logs of the decision to delay SystemD, and some well-informed comments of reactions.
I stopped caring about boot times ever since I became single booter
SystemD is about daemon management. Launching, restarting an restarting them. Benifits are more stability in case of a daemon crash; self-healing capabilities without restarting other related daemons (dependancies).
SystemD also only leads the bare nesecary daemons, meaning less RAM and CPU usage; the bare minimal and on request, so you never have to start a daemon yourself.
Just one of the advantages is faster boot times due to bein able to launch multiple daemons at once, even if the have depencies. This is also useful for launching daemon during runtime.