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 other appliances. This is not possible if all the appliances are 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 are connected 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.