When I first saw this, many years ago, I thought it was rather baroque.
When I first *used* this, a few years ago, I started to see its charm,
especially in being able to easily drop in new services.
When I first administered a BSD system a couple of years ago, I came to
be quite irritated by the /etc/rc arrangement:  in particular, it's
quite annoying that every time I install the latest /usr/src/etc/rc.local
to pick up some useful change, I have to re-edit it in order to put back
all of the "local" changes I've made.  Granted, there are other solutions
to this problem than /etc/rc.*, but it was far easier to customize the
System V scheme without having to touch the original scripts.

What customizations do I have?  I start pppd from /etc/rc.local (before
kerberos), I start up innd and httpd, I change the ldconfig line to
add the X11 libraries, and I load the X11 aperture driver.  An official
change to rc.local that would make *me* happy, at least, would be to have
rc.local finish by invoking rc.local.local if it exists, AND to have the
ldconfig line somehow figure out if it should do more than just the default
libraries (perhaps a file in /etc listing what directories (if any) it should
add).  However, there are probably many other people with different changes
that wouldn't be made happy by that arrangement; I think it's just *better*
to be able to administer a system by bolting stuff together (i.e. dropping
new things into a directory) than by having to saw it in half (editing a
file whose changes are going to get smashed the next time you upgrade).