Oh for god's sake, not this 'working mothers are to blame for all of society's ills' drivel again. Ok I haven't read the actual report, but the way BBC is reporting this (without challenging any of the assumptions in the report, or even worse, presenting the report in a particular light) is shameful.
The way words such as 'selfish' and 'individualistic' are thrown around with a very clear assumption that this has to do with working mothers is also shameful (and so so predictable & boring).
As for the substance of the issue, whether children are more unhappy today than they were in the past. To be honest, I find the whole thing a non-issue. The 'past' is a very general, vague thing; the way things were in the past were different from town to town, from household to household, from country to country etc. I agree with everyone who wrote about our ridiculous idealization of the past, especially the '50s. There was no such ideal past, it's simply an illusion.
One thing that I do think is a real problem in today's world, is the fact that children don't have independent space & time of their own. They're always with an adult present(particularly in big cities). When I grew up (and I'm 35 now, so not THAT long ago), I was able to roam the streets with friends, especially during the summers, play, discuss, fight, create our own rules, without our parents. I think this is a huge change in today's society and it really influences how children experience their life. So that could be a change for the worst... I personally think all the rest has to do with economic difficulties (again, especially in big cities where property costs what it costs) & definitely has little to do with 'working mothers' or the 'break-up of marriage'.