While Lolita is generally acknowledged (correctly) as having high literary value, its success was greatly boosted by the place and timing of its publication. Unable to find a US publisher, Nabokov agreed to give it to Maurice Girodias' Olympia Press in Paris, a firm then renowned for its dirty books. Anglophone travelers (I was one) would flock to Brentano's in Paris to stock up on these racy titles.
Lolita was originally published in 1955, heralding the collapse of literary censorship in the US and the UK. Thus the book's success reflected a confluence of intrinsic value and external circumstances. For those who lived through this era, Lolita was indeed central - as it is to anyone who seeks to understand those remarkable years.
The Stanley Kubrick film is also good, though it fudges by advancing Lolita's age from 12 to 16. Nabokov had taken up this theme of girl love several times before in his writing, yet, to my knowledge, he had no personal interest in behavior of this kind. I suppose curiosity goes beyond what we actually do. I have a mild interest in BDSM, but no ability to practice it.