You're obviously desensitised!
I forgot about the guy in the bag and the implications that come with that image. Also, it probably is more disturbing than Jacob's Ladder to begin with...
I think I am not just desensitized to this sort of films but to immersion into movies in general. I have been reading about special effects, movie techniques etc. for years and nowadays often am more amazed about how they did it rather than shocked that they did it or what was done. It occasionally saddens me, as feeling scared of a horror movie can be, to a degree, an wonderful experience. Drama and Comedy usually still work as designed though.