There's nothing to consider, they ARE Horror. Just a different type.
Which is not my type. I really don't have the heart for exploitation horror, or modern Horror in general.
Give me Vincent Price, an Edgar Allan Poe piece, an old Universal flick, or hell, a thriller horror flick, like Woman In Black. but I don't like shit like Freddy or Jason or Chucky, or any of the modern day exploitation horror films. I just can't stomach them.
(Speaking of Woman In Black, that shit was real good. great atmosphere, and some of the scares, although sort of cheap jumpscares, were well played)
There are a lot of slashers I like. I like the A Nightmare on Elm Street series a lot, if anything, the ones that Wes Craven had more of part of(NOES1, NOES3 and New Nightmare), and love the slicing between dream and reality, and how dreams can feel bizarre and natural at the same time(and how you don't immediately realize you are in a dream, even though illogical occurences happen before you). Hell, I think dream horror in general is an untapped genre. There are so many cool possiblities you can do with the subconscious and hidden demons, being at the will of your own mind and creating your own monsters. Dreamscape did a little of that, and there's been scarce few to try.
I love John Carpenter's non-Halloween work(particularly Prince of Darkness, The Thing, In the Mouth of Madness, though not really horror, I love Big Trouble in Little China, which almost feels like it could be a BEU video game movie). I love the works of David Cronenberg(Scanners, The Fly reboot, Videodrome, The Brood,...) and "body horror". Even horror comedies like Fright Night(well, horror with comedic qualities), Return of the Living Dead, Night of the Creeps, and Monster Squad(I always though Dracula was badass in that one). My taste seems to vary from the old horror to the 80s(mainly). There's some other movies I like scattered throughout the 90s and 00s(even a few now), but I haven't found that many good ones lately(compared to older ones). Even the more schlockfest cheesy b-movies of the 50s-80s have more heart than the same caliber films of today. SyFy original movies just don't do it for me. It almost feels like modern b-movies just miss the point and charm completely.
Talking about good atmosphere and bringing up Woman in Black(the original, which I think is superior to the Daniel Radcliffe remake), I think the movie The Changling(1980) has some damn fine atmosphere and tension. Doesn't hurt that it also stars the awesome George C. Scott!
The Changeling (1980)There are many slasher flicks which have heavy mood and horror beyond "stabby stab-stab." Many of these are gialli (Italian murder mysteries) and what you could call "proto-slasher," but they bear much in resemblance to the recognized slasher/bodycount genre.
Not to mention Phenomena, which inspired the Clock Tower series. Horror and horror video games tend to go hand in hand. Clock Tower was inspired by Dario Argento's Phenomena:
Remembering: Phenomena (1985)Splatterhouse was inspired by Evil Dead, Deadly Spawn, Poltergeist and Lovecraftian creations. Castlevania was inspired by classic Universal(and Hammer) horror, and as I said elsewhere, probably even continued to be inspired by horror movies up until OoE, as Leatherface was obviously nodded to:
Interestingly enough, it's based off the original Leatherface(not the reboot one):