They may not have had the free-roaming childhood of many Gen-Xers where you spent all day out riding bikes and playing ball games in the street, but they seem more aware of the risk of sitting at an office job through the day, and then sitting in front of the TV in the evening.
I like our trains here in Sydney for similar reasons. The lines are almost all aboveground, you get to see plenty of neighbourhoods and plenty of sunshine out the windows (you also get the full panoramic scenery when going over the harbour bridge). And they're double decker and have lots of seating, so there's not nearly as much shoulder jostling as on typical metro trains (although there is frequent squeezing past peoples' knees to get out of a window seat).
Ironically, there is a brand new "metro" line here in Sydney (and they're building more metro lines), and many people prefer it - even though it has less seating, is often crowded, and is more underground - because it's faster and more reliable. Opposite of the situation in London. I guess the grass is always greener!
You don't even the "Wombling free" grafiti they often attract.