Eric Naiman argues that people insist -- despite Nabokov's objections -- in a political reading because they need to rationalize their appreciation of something upsetting to them. In short: cognitive dissonance.

"This anxiety revolves around the social, real-world usefulness of read
ing Nabokov. In this respect, Lolita may stand in for literature or fiction as a whole, but Nabokov seems especially to provoke this anxiety because he so firmly insisted that his work had no moral in tow, and because he deals so
richly —on the level of content— with transgressive issues that often lead
scholars to adopt redemptive, socially justifiable strategies for their reading and appreciation."

Dante