From the sound of it, we can all agree that no BC is 100% fail proof (even vasectomies and stuff).
We can also agree that abstinence is, but isn't terribly realistic.
And that people shouldn't plan to have more children than they can take care of, though people have varying definitions of what children need.
Back to the OP, I don't see not being able for afford presents as an income problem as much as it's a, they don't care to try problem. You can always find a way to get your kid presents if that's something your family views as important. Not ipods and game systems by any means, but you can usually find new in box toys at the local thrift stores, and at garage sales. My parents were really poor when we were kids. Way below poverty level, but they didn't go on public assistance. They couldn't afford to run out and drop hundreds of $$$ on presents every Christmas, but we never knew it by the kinds of Christmases they gave us.
We'd get up and there'd be a stack of loot obscuring 3/4 of the tree. lol. Most of it they picked out throughout the year at garage sales, because you really can get nice new stuff, even in the package, if you look. They probably paid less than $50 to give us so much awesome, and it's not because they were rich. It's because that was something important to them so they found a way, even if it meant getting something that was a good deal 5 months ahead of time and hiding it until Christmas day.
That, I think, really shows what makes a devoted parent. Not so much that they gave us tons of loot, but that they thought so many months ahead of time and prepared within their means so that they could give us something that was important to us.
I wouldn't have traded them for the world, and am grateful I had such loving parents even though we weren't well to do.
FWIW, my brother is pretty wealthy by most people's standard. He has four kids. They don't do birthday presents. Instead each kid picks a day trip they'd like to make and the family goes out together. That's almost better family-wise than buying a bunch of crap.