Life too seems busier than yesteryear with more pressure on time, folks working longer hours, commutes, demands of life, family, etc. It doesn't seem that long ago folks knew how to change a plug, put egg white in a leaky radiator to get a car home, use ladies nylons if a fan belt broke, or clean the contacts on a distributor cap if it got wet! Times move on, ladies don't wear nylons anymore, cars have electronic ignitions , cars only need light servicing every 30k, most folks never have to lift the bonnet of a car from the day they buy it to the day they sell it except to put windscreen washer in it. I guess its the same with model railways. Loss of time, loss of desire to kit build = loss of experience and skills, hence greater demand for RTR especially as there is now plenty of RTR available unlike 20 years ago. Also materials have moved on.
Another hobby of mine was RC aero modelling. I usually scratch built from plans, or the occasional kit, and then ARTFs and RTFs started dominating the scene 15 years ago, now hardly anybody builds anything, its now more of a 'fit out' operation - way of the modern world. Also there was a huge shift away from traditional materials such as balsa, spruce, and lite-ply, to modern materials such as fibreglass, carbon fibre composites, synthetic coverings and resin paints.