Turoskel, it's just like if you got Seasons. You would be able to set the Seasons settings for the first time because you couldn't before. This is your first availability to change the occult settings, so you can do it. You can also set the moon phases (or phase, if you prefer). Just don't change the vampire setting or celebrity settings since you had those before.
I would also like to add that Varg's Tavern, The Red Velvet Lounge, and The Toadstool are other buildings you can only now add to your town. Don't know why you would since you don't want supernaturals, but whatever.