On should note that some of the works Lovecraft mentioned were not supossed to be a part of th essay per se, like Northanger Abbey . Others, he simply called out on being horrible .
I'd take issue with that concerning
Northanger Abbey. It was very much a part of the essay, as he was discussing how the Gothic had, by that point, become so insular and incestuous that it became very fair game for parody -- which Ms. Austen did delightfully, even affectionately, well. It remains still one of the best and most intelligent of such responses to a genre which was becoming quite moribund, and so an important part of the history of the weird tale, even if it is not weird in itself.
And yes, he did remark that several of the others were quite bad -- including Lewis'
The Monk, when taken as a whole... as well as most of the books at the beginning of the "Aftermath" chapter. These would include the
Horrid Mysteries,
Children of the Abbey (which is actually not that bad, but scarcely a weird tale, however strongly influenced by them),
Zofloya, and Shelley's little essays into the form... as well as G. W. M. Reynolds' pieces. I've read all but one of these (
Faust: A Romance of the Secret Tribunals, which I've not been able to track down), and I have to agree with him, in the main.
Zofloya can be fun, and it's certainly the best of the bunch, but it is often dreadfully silly, melodramatic, and confusingly written. As for Shelley's two pieces -- which are indeed imitations of
Zofloya, among other things... as stories, the less said about them the better... he even completely plagiarizes the ending of Zofloya in one of them, to the point where the phrasing is almost ridiculously similar. They do have their points when it comes to a study of Shelley, or the literature of the period, but otherwise... they're tripe.
On the other hand, Lovecraft was less than impressed with some writers who are titans in the field, such as Le Fanu. He also didn't much care for Wells' weird work, finding the handling quite tame. (I don't always agree with him on this one, and definitely don't when it comes to Le Fanu.) He never cared much for Scott, either, putting him in with other Romantics whose work he felt was artificial and forced, but some of Scott's work (and that of Stevenson, another writer he rather scorned in general) did merit his approbation.
Lovecraft was definitely one of the greatest theorists the field has seen since Poe, but he did have his blind spots, as well as his strengths....