You do rather seem fixated on the luxury lives these people are supposedly living.
Having two wage earners doesn't mean that you can necessarily afford a big house, multiple holidays or even dare I say it a BMW on the driveway.
Our small 2 bedroom (the second being a box room) house costs 900 a month in mortgage payments, prior to the interest rates dropping it was around £1200. Before our daughter was born we would have fitted in to the 'high earning' group that you have referred to.
We still both work but have gone part time so that our daughter goes to nursery twice a week. She gets attention from both her parents throughout the week and also gets to socialize with other children and adults on the days that she attends nursery.
We certainly do not lead a luxurious lifestyle. Our income fell by around 20k when we went part time. We haven't had a holiday since 2006 (our Honeymoon), though my wife does have a Radley bag (rather threadbare as she's had it for years). We don't go out, we don't drink, we don't smoke. Our wages just about cover our bills, food and petrol.
We've both paid taxes for years and the amount you get isn't a huge amount (£40 per month) but it helps.
"Then maybe couples who want children should have the most help and support"
So in order to want a child or to love a child you have to not work?
Isn't that one of the social problems that this country is facing at the moment, plenty of people who don't work and have never worked having lots of children paid for fully by the state and ultimately the tax payer.