Seeing most of the stuff Kodama Naoko puts out and what kind of yuri she tends to be interested in, I always imagine that she’s kind of bored drawing this kind of manga.
She talked a little bit about this in the first part of an interview she did somewhat recently. Two quotes that I think give a decent picture:
"After A World Without Freedom, I let loose a bunch of darker works, so now I’ve started wanting to write lighter things again"
"The ratio between “I want to express my own feelings,” and “I want everyone to enjoy reading” has changed from about 8:2 to 3:7."
I really love dark Kodama, but we probably won't be seeing much of her for a while. Light Kodama is great too, so it's not too bad.
I couldn't link the interview without the filter accusing me of spamming, but googling the quotes should work.