Some ideas are obvious in hindsight. For example, keyless ignition is something I thought was absurd and later thought was a luxury. There's not much about a physical metal key that makes it secure. Absent deep knowledge about the role of a key, I'd formed my own ideas about how a key makes your car safe. The lack of foresight also means we are not willing to give up on clearly bad ideas. Because then current hand held devices are rather low powered, my thought was it is better to have a separate device for each function such as listening to music, checking email, phone calls, and so on. I don't think I'd have invented the iPhone if you gave me a hundred years to do so.