In a house, there are many electrical appliances that have to run independent of each other. If one appliance is turned on or off it should not affect the other appliances. This is not possible if all the appliances were connected in a series arrangement as there would be one switch that either switches all of them on or off.
When appliances are connected in a parallel arrangement, each of them can be put on and off independently. This is a feature that is essential in a house's wiring.
Also, if the appliances were wired in series, the potential difference across each appliance would vary depending on the resistance of the appliance. This would make it very difficult to provide the right power to flow through the appliances. When house wiring is done in parallel this problem does not arise as the potential difference across each appliance is the same and equal to the potential difference being provided by the power company.
In parallel circuit arrangement you get the same voltage for all circuits as at mains. You know that all the electrical appliances are designed for a standard nominal voltage. This is the only arrangement where you can ensure the required voltage to your appliances at home as provided by the power supply company.
A series arrangement will have the obvious disadvantages that unless all the appliances are not turned on, the circuit will not complete and no gadget will operate. But more importantly there will be a voltage drop associated with each of the electrical appliance and your gadgets will get a low voltage than required and may get damaged. And even if it works, it will not give you the rated/designed output.