Another thought on Ross Douthat's continued view that women aren't getting married and having enough babies because they're decadent was inspired by listening to Brazilian indie band CSS's excellent "City Grrls" on the walk to the office this morning:
This song obviously contains important elements of decandent think ("I wish I would dye my hair pink / Put on black lipstick / No one would give a shit / Short shorts short skirts flower tops denim shirts in the big city") but that misses important elements of the context for this fantasy. Her dream is of "being dizzy with my job and my gay friends / laughing and drinking with my one night stands." She's partying, yes, but that's inextricably tied to the idea of being dizzy with her job.
The mantra isn't that she wants a life free of responsibility and discipline. Rather "I wanna walk around free on my own / And pay my bills with the money I make." What she wants is to be independent. A job, obviously, can be a drag or even a nightmare. But particularly from the viewpoint of a woman coming from a traditional religious society it can be very liberatory.
You show up, you do your work, you get your money, and then you get your time off in which you can do what you want. In a man's voice, the basic vision here would really be exceptional bourgeois. It's not a decadent slacker fantasy, it's a basic work hard and play hard quest for individual autonomy. And it's obviously true that having children—especially a large number of children—would tend to compromise that quest, especially without a male partner willing to fully bear his share of the load. But since you don't need to find a partner as a teenager for economic support, it's easy to spend a bunch of adult years deliberately avoiding settling down (see Hannah Rosin's "Boys on the Side") and then have kids later in life but not so many kids as to be unmanageable.