Quoted from phil-lee:

Many of these people were right (I prefer to avoid the agist euphemisms). Pre-50's cars, model trains, antique engines, tube radios, component stereo systems, wooden boats/vintage outboard motors, vintage guitars/amps, collectable dolls, tobacco memorabilia, garden tractors, knives, cast iron collectables including cookstoves, Hoosier cabinets, farming items including tractors, horse-drawn equipment, all have dropped in price and desirability and beg for new,younger people to take an interest. They still have aficionados repairing, restoring, but the average age from these groups is growing older with few younger people to replace them.
Its just a fact of life, each Generation covets those items they grew to love as a child (sometimes).Pinball machines are large, expensive, difficult to repair and the novel artwork sometimes loses meaning or becomes offensive.
If you are ever in Kansas visit the player piano- Nickelodeon museum. Very similar.