configuration file and folder /etc/torrc + /etc/tor.d/
/etc/tor/torrc becomes /etc/torrc
new folder /etc/tor.d/
/etc/torrc comes with reasonable defaults (just the same file as /etc/tor/torrc currently does).
/etc/tor.d/ can be used by third party applications. For example a blogging software wouldn't need to ask the user to modify torrc or to somehow hack it, it could just drop a file inside /etc/tor.d/.
Or someone could make a package tor-flashproxy, which installs /etc/tor.d/flashproxy which makes the machine a flashproxy.
If you ever add new comments to torrc or new (default out commented) options, there is no conflict with other packages relying on torrc.