Why are home appliances and other devices made to operate on dc?
As someone mentioned, appliances which have motors in them mostly run on AC -- however appliances that contain a motor and also contain some form of electronics run on a combination of AC and DC. AC is used for the motor(s) and heating elements(s), and DC is used for the electronic controls (like the control panel of a coffee machine).  These electronics will be used to control the motors or heating elements in the appliance, using a device called a TRIAC (which allows a DC voltage to control an AC voltage).

There are some appliances that only need AC, such as a garbage disposal or simple toaster.

Electronics cannot run directly on AC, it needs to be rectified and filtered to provide a smooth DC to power the electronic circuitry within the device with a constant voltage. Many electronic circuits have several different DC voltages in the same device. 

There are two kinds of circuits: digital and analog.  Digital electronics uses two states, 1 (high voltage, which is the same as the supply voltage) and 0 (low voltage, called ground).  If the power supply were AC, then the logic 1 or high state would constantly be changing, and the digital logic would no longer work.

Analog electronics includes such circuitry such as an amplifier to drive a speaker, and once again powering this circuit with AC would not work.  You would have a combination of the source material (audio input) combined with the alternating power supply voltage, and get garbage coming out of the speaker or headphones.