Pre Stone Age: No one would want stone tools and weapons. They're to complex. Wood tools and weapons are fine.
Stone Age: No one would want copper tools and weapons. They're to complex. Stone tools and weapons are fine.
Copper Age: No one would want bronze tools and weapons. They're to complex. Copper tools and weapons are fine.
Bronze Age: No one would want iron tools and weapons. They're to complex. Bronze tools and weapons are fine.
3rd Century AD: No one would want a sawmill. They're to complex. Hand saws and axes are fine.
13th Century AD: No one would want a gun. They're to complex. Swords, knives, maces, clubs and polearms are fine.
1684: No one would want a semaphore line (optical telegraphy). They're to complex. Letters are fine.
1698: No one would want a steam-powered machine. They are to complex. Beasts of burden are fine.
1753: No one would want a telegraph machine. They're to complex. Semaphore lines and letters are fine.
1876: No one would want a telephone. They're to complex. Telegraph machines and letters are fine.
1886: No one would want a gas-powered machine. They're to complex. Steam-powered machines are fine.
1900 No one would ever want to drive a car, they are expensive, hard to operate and look funny.
1920 No one would ever fly a plane on a daily basis, they are too dangerous.
1970 No one would ever use these computers at home, they are only good for scientists.
2008 No one would need an OS in their phone, it's hard to use, drains battery, phones are for calling!
Let's also not forget things like:
1990 Why would anybody need a hard disk larger than 100mb?
1996 Why would anybody need a hard disk larger than 1gb?
2008 Why would anybody need a hard disk larger than 1TB?
2015 Why would anybody need a digital currency?
