I'm definitely +1 on splitting out the core and auth models/tables. If installing them is just as simple as running init and installing the admin app is now, what's the big deal? For those who want it, it's no harder, and you'd be able to install the admin without even realizing you're installing the core and auth models. But for those who don't want it, you're stuck removing them by hand.
Also, having tables which aren't being used may not be a big deal to your average user, but in a situation where you want to implement a django application over an already existing database, especially in a corporate environment, having pointless tables may not be an option.
