Warning: Did not read through all the posts
I think the biggest problem for occult is that bard is the face of it. The idea of separating the weird Cthulhu-esque and wholly mental/spiritual side of magic from the Fireball and Wall of Stone side makes sense. But they are both still the domain of wizards to me. A wizard should be able to crack open books on Cthulhu and learn how to cast occult spells or go to wizard school and learn fireball. The methodology to becoming an occult or arcane scholar *should* have the same grounding of learning and applying that knowledge compared to Divine where a cleric acts as a conduit for a being of great power or Primal where druids learn how to control nature by being in tune with in.
Instead Occult is represented by the bard who casts spells through performances. The only way to become an occultist, without being born with the power or connecting with otherworldly beings and becoming a vessel for their power, is to be a master performer (and before anyone says bards don't need to be performers, every bard knows how to cast with an instrument and song, knows a composition cantrip, and starts with performance at trained. Even if your bard never stands on stage or uses his performance skills, a prominent aspect of the class is being a performer). I don't mind that the bard is an occult caster, they cast in an unorthodox way using cobbled together knowledge from various questionable sources to make it work and their focus is much more on the mental/spiritual side rather than the physical side. I do mind it being the only way. And regardless of the lore put out by Paizo that tries to separate the image of Occult from the image of bard, bard being the only pure Occult caster makes it impossible.
My personal fix is just letting the wizard pick between Arcane and Occult. The spell lists aren't that differently balanced and it lets the occultist have the image of an semi-crazed hermit pouring over cryptic tomes and ancient knowledge rather than charming halfling who usually plays the lute at the local tavern but moonlights as an elder mythos cult leader (not that I've never used that idea before). I also let bards use Arcane instead so they can focus less on the esoteric and more on cobbling together knowledge to create more tangible effects.