Vanity Fair

I'm reading Vanity Fair this week, and discovered Thackery seems to share Hugo's tendency to apologize for aspects of his novel. Take, for example, this excerpt from chapter 6:

Or if, on the contrary, we had taken a fancy for the terrible, and made the lover of the new femme de chambre a professional burglar, who bursts into the house with his band, slaughters black Sambo at the feet of his master, and carries off Amelia in her nightdress, not to be let loose again till the third volume, we should easily have constructed a tale of thrilling interest, through the fiery chapters of which the readers should hurry, panting. But my readers must hope for no such romance, only a homely story, and must be content with a chapter about Vauxhall, which is so short that it scare deserves to be called a chapter at all. And yet it is a chapter, and a very important one too. Are not there little chapters in everybody's life, that seem to be nothing and yet affect all the rest of the history?

When, I wonder, did authors stop interrupting the flow of their stories to address the reader directly about the mechanics and structure of their writing? I'm trying really hard to view this as a difference in style, and yet I can't suppress the feeling that this is just bad writing. Even if the author is Thackery or Hugo.