I think the real attraction is in the new perspectives you gain from reading things like biographies of people who have committed heinous acts, or accounts of terrific things.
To put it in MBTI speak: Our Ni function "wants" (well it's not an entity so it doesn't want...but you get the point
) us to have all the perspectives, the good, the bad, the ugly, to "see" everything at once, to have all the possible ways a thing can be viewed in a non-discriminant way. Then we use the secondary Fe to judge the best (socially and humanely speaking) possible perspective to "endorse". That's where we say "In my opinion this is good and this is not...". More the information (termed loosely...experiental, scientific, anecdotal...you name it, someone's painting on the matter of let's say "Marriage" provides a kind of information to store away).
Inferior Se I think manifests when INFJs, because of one reason or another refuse to shift perspective and state something "just is specifically that way no other option.. " and I think it's understandable being Fe empathic. It's taxing to take some POVs into consideration.
The thing, from someone else's perspective is it's of course impossible to discern wether this is happening because sometimes the obstinacy in stating an opinion is because it's actually a Ni type conclusion, with nuanced intricacy and considerable background info behind it and infact a very educated and enlightened "opinion", carefully deemed as the best perspective, instead of just being a run of the mill half assed "opinion" like some think. One that's literraly just from the perspective of one ego identity, unable to see multiple POVs.
Yet sometimes because (in my case often of emotional reasons...like someone betraying my trust I might really refuse to look at it from their POV because I don't want to absolve them because I'm angry. Note though that even if I did I might judge the best perspective to be "being angry at someone" and take that course of action and still cut them out of my life or whatever what might happen. All this is internal and left to one's conscious)
Sorry for the ramble... What I'm getting at is that sometimes an attraction to the macabre is less an emotional attraction to macabre things or actually being macabre and more collecting info on macabre and of course the emotional experience is info of sorts too... X) ...I'm very rambly today...my apologies (suffering from insomnia lately)