I guess, I don't see it as all that much additional work for most people;
as you note, most of the time, you don't need to change anything, and the
default cases are correct.  The advantage of run levels is that it makes
it easer to define new cases specific to your site, while preserving the
default states for everything else.  So, if I define run level N to be
"the way I want the system to be while I'm putting up polite little messages
explaining downtime, but allowing people to connect to read them, and
shutting down mail, news, and http, but leaving /home exported over nfs",
I can do it *once*, and then be done with it; this is probably a win.

If you don't want it, well, nothing happens.  A few things move around
a bit, but "shutdown now" still works, "reboot" still works, and "halt"
still works.  Everything else remains functional.

It looks to me like a signifigant added functionality, and the cost in
simplicity is pretty minor; in fact, I'd consider it a negative cost.  After
all, you go from a large script which may or may not have undocumented
dependancies on order of operation, to a set of scripts with identifiable
names which describe each run state; you can tell about what a run state
is without even reading them, and if you want to know where X is started,
it's easier to find the right place quickly.

-s