Why indeed? This film is one of those which can be examined in detail, the meanings and interpretations pored over ... and yet as a film, it is really not that enjoyable, mainly because it doesn't make much sense, eschewing style and interpretation over actual plot. Much of the film seems to consist of people running about an old house, along corridors, up and down stairs, and opening and closing doors. The director has a habit of focussing the camera on certain apparently unimportant elements in shot rather than actually trying to create a meaningful narrative, and so the viewer is left wondering what is going on.
When you add to this a soft porn element, such that the women are beaten and abused sexually, with the camera lingering on blood on flesh, buttocks and pubic regions, then the film starts to move from being a horror film (which perhaps it purports to be) into some other genre of voyeuristic and tacky film making.
There are some aspects which I liked. The incidental music is electronic and atonal, and works to highlight the action well. Kier is very good as Jekyll as I say, and some of the camera work and lighting is very nicely handled. Overall for me, though, it's a thumbs down. Not a film I suspect I will be watching again.
As usual, Arrow have included an impressive package of extras, including two short films by the director, interviews and documentaries exploring his work.