Most couples self limit these days, for precisely the reasons I mentioned. They may not think of the things they have as luxuries, but believe me, families who chose to have several kids instead of always having a fairly new car, or the biggest house in the neighborhood, or trips to Disney every year, think of those things that way. Not that the families with more kids necessarily want those things; they are not as important to them as the love and fun times generated by their families.
We have four kids, and we never took them to Disney, Our kids never asked to go, mostly because none of us can stand giant crowds of people. The year we celebrated our 25th anniversary, we bought a brand new car; our first.
Different families make different choices that seem right to them. As long as a family is working and supporting all their kids, I don't care how many, or how few they have, whether they're stone poor or living in the lap of luxury.
There are lots of good reasons not to have kids, and there always have been... IMO it's a good enough reason not to have kids if you just lack the desire for them. No one should have to justify their desire for kids, or lack thereof, to anyone else--they just have to support them if they choose to have them.
IMO, there's nothing special or praiseworthy about people who mindlessly churn out offspring, with not a clue about what they're doing, just because someone else told them it was their "duty" or that they "should" want "as many kids as God gives us."
Back in high school, I knew girls who were so eager to have kids that they couldn't wait to graduate before they started popping them out.
I also knew at least one girl who was adamant, at age 16, that she never, ever wanted kids, and she was highly pissed that she was too young to persuade a doctor to tie off her tubes. BTW, she came from a large family where most of her siblings had at least several kids (one of her sisters wanted lots of kids), and she didn't have very much ambivalence about men that I could see.