People have an interest in the psychology of premediated murder.
if someone panics and reacts by killing, or gets drunk or snaps, the psychology is quite predictable...but calculated, planned, organised, sometimes for months, murders are always of more interest.
i think the jack the ripper case is also of interest because he was never caught and that he was apparently of some nobilty.
it was also unheard of, so more shocking.
i think he'd have been caught in a shot nowadays