A brief and only partly-formed thought follows:
(also thoroughly pilfered and likely better described elsewhere by others)
While listening to the most recent Elder Signs podcast I began to reflect on the strengths (and possibly the flaws, or at least common criticisms) of WHH's writing. Like many writers of his time he was dabbling in various writing forms, essentially looking for a "hit" with which to produce an income. It strikes me that the structure and variety (some would say the variable quality) of his broad literary legacy is probably somewhat reflective of his effort to combine or experiment with what we now know as genres and tropes. The Night Land, for example, is a science fantasy tale, somewhat in the tradition of contemporaries like HG Wells, but it's mashed together with this kind of "high romantic" language and characterization that was dated even for the time but was a throwback to older heroic stories. The Ghost Ships is (well-named) a mash-up of a seafaring adventure and a ghost story. Carnacki mixes ghost tales with detective fiction (sometimes leaning toward the supernatural, other times leaning toward the technical). I guess what I'm saying is that WHH may have been intentionally frankensteining together different types of tales he had read (either because he enjoyed them or thought they would sell) to see what would work. In a way I kind of read him now as a primordial hollywood hitmaker saying "what we really need now is a teen romance but with vampires and an axe-murderer." At his best he created seminal types of fiction. At worst, entertaining tales which have odd blips in the prose and lack of focus on characterization and motivations.
Anyway, end of rant. Feel free to disagree or discuss!