[Jasper_]

/usr should be mounted at the start since there's various things that are necessary during bootup, like udev rules.

See http://freedesktop.org/wiki/Software/systemd/separate-usr-is... for a more complete explanation.

There's no equivalent for /usr/share, which some programs depend on. You could make /share, or you could just use /usr for everything and have it available at early boot. Putting everything "system" in /usr/ also lets you make backups more efficiently instead of having to blacklist /home/, /sys/, /proc/, etc.

The initd needs to depend on the kernel. POSIX semantics aren't enough. Even Upstart and SysV init change their behavior based on the kernel.

Furthermore, it makes sense for the responsibility of services to be delegated to one place, otherwise you end up in this situation where programs are started differently from cron than they are from /usr/bin/service than they are from init. It makes sense to delegate all the complex service management and watchdog stuff to one location, and that requires kernel-level semantics. For instance, systemd's use of cgroups allows CGI that it forks off to be killed when it tries to stop Apache.