The use of blood and gore invokes different reactions based on how you're using it, the same as what you describe. I would attest that it is generally intended more to shock than to outright horrify, though of course this varies between films, directors, and stories. I'll take as an example that poster child of "it's just torture porn" upon its cinema release, the first Saw film. Its use of very graphic violence and blood is designed to emulate the violence that Jigsaw believes the killers have themselves inflicted upon the world; it asks the audience to consider that violence, that pain, that suffering, and then think about how justified this retribution is. In similar (severed, oozing) vein, Hostel and its sequels are critiques of capitalism and capitalist society's distance from the violence upon which it is built - violence against marginalised peoples and the global poor, and the vengeance that the global poor are carrying out. I'm not saying that these critiques are entirely successful, nor is every gory film some secret masterwork of anticapitalist theory. However, I do think it's disingenuous to dismiss every film that uses graphic imagery as "relying on" it in lieu of different styles of horror which might not fit the ethos, atmosphere, themes, et cetera that the director was attempting to convey.

For a more in-depth look into this, I recommend the excellent work of feminist film theory, Men, Women, And Chainsaws: Gender In Modern Horror Film by Carol J. Clover.