The thing is though, even as an occult player I can create diversity in the game if and when I want to. The majority of my played Sims are either gay or bisexual, I've played entire storylines with transgender sims, I can go into CAS and create a Sim from any background or culture I want depending on how I actually create that sim, to a certain degree I can even go into the holiday calendar and create my own diverse cultural celebrations in a sims calendar year (it won't be perfect, but it's still doable), and depending on what expansion packs you have you can utilise additional game play to make the sims world feel more diverse.
Here's what I can't do; I can't turn a sim into a werewolf; I can't realistically create or interact with a faerie sim, beyond mere window dressing or superficial dress up (or attempting to work out how to utilise a non related pack to cheat to high heaven and still not get any actual game play mechanics); I can't summon a dragon, or befriend a unicorn, or have a sim return from the dead as a zombie, or pretty much anything else occult related that doesn't exist in the game at all.
There's already enough 'Pollyanna' realism for the realism players, there's already diversity and the opportunity for self directed diversity gameplay for the players who want that as well (I would count myself among them), but for those of us who want to play outside the box with fantastical worlds and life states, well it seems like we get tossed the scraps whilst everyone else complains about the lack of already existing features of the game.