I personally found that calling this indecent is really pushing it. Maybe because it presented some light erotic ideas in an unexpected medium (a young girls stream of consciousness).
Maybe its like how people called marijuana a "gateway drug", because after all of the breathless hype about how great it is and how it will immediately ruin you life, the people who tried it were mostly disappointed. If the authorities were so wrong about marijuana then heroin can't be that bad.
I am certainly not saying it’s actually obscene or indecent! My point was that the scandalous bit was really quite prominent at the time of publication and not buried in an 800-page novel.