I agree that there's a time to live in lots of different places. What works perfectly for a teen isn't the same necessarily as for a 40 year old and of course lots of teens and lots of 40 year olds want different things too.
I think most of us hanker after something of our youth. It might be where we spent our teen years or more likely where we were students or spent what now seems like carefree 20s. One of the things about carefree 20s is that is was usually spent where we chose and not our parents.
I'd say that if you live in the burbs of zones 4,5,6 or in the Home Counties with fast direct travel to London in less than an hour, there is access to the stuff Lomdon has for you and your kids. It's not the same as having your corner shop as some wonderful ethnic supermarket that you only find in a certain part of London, or nipping to a gallery on a whim and being there in 10 minutes, but for those who want access and regular access it is ....accessible burbs and home counties.
For most small children, a garden is worth a lot. For most teens, fully accessing all Lomdon has to offer won't happens here've they live , but for those who want it, it's there for all those who can get in easily at the weekend. And then, when they are in their 20s, if they really want central London living, then is the time to have it, because they can choose and they can make if it what they will, which is why so many of us love it - because we chose to do it in our 20s. And maybe we will do it again in our 50s or 60s......or just choose to travel in more frequently from the burbs and Home Counties, whilst also enjoying gardens and spare rooms.
Life changes and so we live in places that suit us for the time we are in now and which might not have suited us in our glorious youth or imagined golden retirement, but which give us the best compromise for everyone in our family now. More private inside and outside space feels like a need for most growing families and drives them out, but if you think speedier access to cultural highlights and diversity etc etc is worth more, then remaining might be right....even if it's just for a short while longer.