I think that Humbert's construction of himself as an artist is one of the primary driving forces behind his aesthetic. Little remains clear. Humbert's entire narrative is a combination of memoir and revisionist history. Consider the thoughts of the narrator in the Foreword: "entranced with the book while abhorring its author." Such an aesthetic becomes the basis of Humbert's recollections. There is little absolute. Almost as confusing as Humbert swerving and driving on the wrong side of the road, Humbert's sense of aesthetic in the composition of his narrative is one in which "suffusion of swimming colors" abound.
Humbert uses this blurring to help enhance his own aesthetic. Nabokov uses this to enhance the narrator's unreliability. This aesthetic is what enables the reader to see Humbert in such a complex light. Precisely because events are immersed in "swimming colors," the narrative is one in which cruelty and pain become the only constants throughout. It is this aesthetic that Nabokov suggests is part of the modern setting. Humbert depends on this notion of a lack of clarity and certainty to be a part of his aesthetic and narrative mode.