It's my belief that the lack of interest shown nowadays is directly due to the influx of cheaper and more reliable vehicles, domestic appliances, computers, plant and machinery over the last few decades, combined with a massive reduction in replacement costs and modular design incorporated in almost everything we use.
Those of us who were children in the sixties and seventies were used to seeing people performing their own maintenance and repairs on cars, motorcycles, domestic appliances and anything else you can imagine in driveways and garages wherever we went due to the user-serviceability, ease of repair, easy access to second hand spares and inherent necessity for regular attention that came hand in hand with any mechanical item of the era. So we saw "dirty hands" as a part of life.
At the age of 15 I was quite able to strip and rebuild a heavyweight 50s-60s motorcycle engine over the weekend with nothing more than a handful of spanners, a tube of Hermetite, a few quid in spares and a flat-head screwdriver, but I wouldn't dream of tackling the same job, in the same timescale on a modern version without a properly equipped workshop and a well stocked bank account, so I'm not at all surprised at the apparent lack of enthusiasm, or experience exhibited by youngsters nowadays.
Most kids today wouldn't give a beautifully built scale mill engine on a pretty wooden base more than a few seconds interest, but use a simple, single cylinder diesel to power something like a car, tank, or even a crane and those same bright, young things will queue up to "have a go" at operating it.. And engaging them like that is the only way I can think of to get them off their Playstations and into the workshop.