Not that I question your personal views or reasons for not playing those classes, and I can definitely see Spiritualist and Medium making some people cringe, but Occultist is pretty different in theme from those two. Occultist is a focus-themed caster-lite, and I've seen Harry Dresden and even Hellboy given as possible examples of Occultists, and arguably the movie version of John Constantine.
It's nothing to do with game mechanics as much as the flavor of the class. I'm kinda averse at this point to the whole "occult/made up ceremonial magick" thing. *shudder*
plus I admit that the more I thought about it, it really was just another way to be an arcane caster. "Hey look, I'm carrying a big staff and am an evoker". Meh. Didn't speak to me as a class. But it's not as creepy to me as the spiritualist and medium now that I think about it.
And if you see me here, please, never be afraid to question me. I encourage you from time to time, and always in a respectful manner, to question my logic. If you're unconvinced a particular post if mines is the wisest, tell me so, but allow me to convince you, and I promise you, right here and now, no subject will ever be taboo.... Yes, I just went all O-Ren.