Greg,

i cant get my head into the space where you're coming from.
Please bear with me for a bit...

The way I see the evolution of hier(7), /etc was for _system_ config
files.  crontabs/at entries are user data (created, owned, and
maintained by users), so they don't belong in /etc.  (I think the
several people with good reasons for readonly roots would read it that
way too).

/var was for transient to long-lived but `volatile' files -- both
system stuff, like log files, and also data that notionally belongs to
users, like /var/mail/j.random.user. 

Okay, so much for history.  Now, you ask where user-writable
configuration information should go.  you point out that /var was a
Mistake(tm); we all have reasons why. (the ones I've seen are huge
systems with tens of thousands of users, to the point where individual
directories don't scale at all well.)

Then you say:

>The traditional answer has been the user's home directory (.forward,
>for example).  These days, a user's homedir might not be accessible to
>cron, though, and people now have an expectation that cron/crontab
>will still work for users under that situation unless it has been
>disallowed.

Okay. Even so, we want to have the per-user crontabs somewhere
`accessible' when the users' home directory isn't. (Even if using
$HOME is cleaner, the users would revolt.).  But once we decide to
make that tradeoff, and put crontabs somewhere central, then doesn't
hier(7> say that /var the right place, and /etc the wrong place?
Would you keep user maildrops in a subdirectory of /etc?

>Not totally; a symlink into something like /var/etc would repair the
>situation.  (Or, alternatively, you could disable user access to
>cron.)

As would leaving the status quo ante and making /var/{cron,at} a
symlink into /etc/{cron,at}, no? So to those who do want (eg) readonly
roots maybe the /etc/cron change seems like gratuitous incompatibility?

Maybe the right answer is another entry under / in hier(7), for
``non-volatile user-owned data that users expect o be around even
when their home directories aren't'', with symlinks to there from the
historical places (/var/{mail,at,cron}, maybe games)?

Sorry for being longwinded (yet again), but I'm genuinely trying to
understand what both sides are asking for here.