That's already what Ravenloft does. Barovia and Verbrek are the horror of being hunted and turned into something other. Tepest is the horror of being tempted by the other. Lamordia is the horror of being reduced to nothing more than a lab rat. Kartakass, Darkon, and Dementlieu are the horror of paranoia. Sithicus is the horror of decay and loss. Richmulot is the horror of contamination. Hazlan and Falkovnia are the horror of human cruelty and unfairness.
The fact that TSR decided to put this into a gothic-fantasy setting is irrelevant to the type of horror each domain embodies.
Lamordia is Frankenstein. Barovia is Dracula. Tepest is the hags from Shakespeare mixed with some brothers Grimm. Sithicus is about as gothic romance as you can get (an undead knight pining and tormented by the woman he loves). Richemulot is all about desolate ruins, and its filled with were rats (not were wolves, but very much in line with classic monster stuff). You obviously have other themes going on in these settings that make them work. Anything like that is going to have other themes. These are not discrete types of horror. These are discrete classic horror domains. If Lamordia was the toxic avenger domain, Sithicus the Saw Domain, Barovia the Dracula Domain, Tepest the slasher domain, Dementlieu the body horror domain, Kartakass the dark fantasy domain, then you'd have a patchwork of horror subgenres. But most of the domains you mention, if not all, are based on classic horror tropes and sources (not on new subgenres of horror)