The word that Scott can't escape is "slack". Rarely is he in a hurry to get anywhere, so he requires patience, perhaps too much at times. The story of The Heart of Midlothian is not told with anything resembling efficiency.But AR acknowledges the charms of Scott's inefficiencies, giving due attention, for instance, to Madge Wildfire in Heart of Midlothian and Wandering Willie's Tale in Redgauntlet. I think we agree that there's more to life than "push[ing] the story forward." (In a comment at AR's place, I tried to imagine Dickens being efficient. Sometimes perhaps writers should do things just because they can--Joe's hat falling off the mantel in Great Expectations, or the head of Charles I in David Copperfield. Constrain that imagination and maybe you don't get Krook's spontaneous combustion, or Miss Havisham and her wedding cake....)
Another interesting comment: "Honor and loyalty - Scott returns to this theme repeatedly. Perhaps one reason we do not read Scott so much now is that we our ideas about honor have changed too much since Scott's time." Scott isn't afraid to showcase virtue, either: I'm thinking of Jeanie Deans in The Heart of Midlothian, almost certainly too steadfast to be the heroine of a novel by any other 19th-century novelist.
Still, the evidence of my very small sample (including those commenting at WutheringExpectations) is not overwhelming in Scott's favour. No question, he's not a crowd-pleaser, but I'm reminded of the annoying ads for local brewery Alexander Keith's: "Those who like it, like it a lot!"