Re: Hasn't this happened already with Upstart?
You're essentially arguing that it's OK for SystemD to use it's own (IMHO crappy) logging system because I can make it also pass onto rsyslog. journald is therefore completely redundant, so why would I want it on my system in the first place?
journald logs stuff that systlog can't, the stdout and stderr of things started by systemd for example.
Also, since it knows exactly which service logged each message it can show you the last messages for every service with the systemctl stautus command, which is pretty cool.
# systemctl status ssh
● ssh.service - OpenBSD Secure Shell server
Loaded: loaded (/lib/systemd/system/ssh.service; enabled)
Active: active (running) since Thu 2014-11-27 10:58:31 CET; 4 days ago
Process: 906 ExecReload=/bin/kill -HUP $MAINPID (code=exited, status=0/SUCCESS)
Main PID: 592 (sshd)
└─592 /usr/sbin/sshd -D
Nov 27 10:58:35 celtic sshd: Server listening on 0.0.0.0 port 22.
Nov 27 10:58:35 celtic sshd: Server listening on :: port 22.
Nov 27 10:58:53 celtic sshd: Received SIGHUP; restarting.
Nov 27 10:58:53 celtic sshd: Server listening on 0.0.0.0 port 22.
Nov 27 10:58:53 celtic sshd: Server listening on :: port 22.