I think any answer to this will have a large degree of conjecture. However it seems likely that this linked to the Gothic novel genre, which was in favour from 1763 to about 1900. These novels would be classed as "horror" now, but were not necessarily low-brow. Familiar examples would include Mary Shelley's *Frankenstein (1818), and Edgar Allen Poe's The Pit and the Pendulum (1842). While they didn't usually involve "on screen" torture, the theme of the Spanish Inquisition was fairly common, so I suggest that the building of the devices you refer to was part of this general fascination.

thanks for answering. perhaps a better question would be what made the gothic genre popular but I suppose that to would involve a lot of conjecture.