Jobs talked about Cars and Trucks. The desktop, and many laptop computers, are trucks. They can do the heavy lifting, converting, number crunching, graphics processing etc. Tablets and smartphones are cars. Calling them "automatic transmission" cars is probably even better. The learning curve is low, the uses are "limited" compared to the trucks but most people don't need a truck for their everyday lives.
The MacBook Air is on the threshold. It's a device that looks like a truck and has the inners of a "sportscar" with a truck-style processor, but the interface of the truck. It's manual transmission but not useful for all truck jobs.
If Apple could ensure that everyone had a data plan maybe they would cut out iTunes. Of course, they still make a nice profit on all those Macs...