Motor Vehicles Act states that every motor vehicle plying on the road has to be insured, with at least Liability only policy. Since a single policy cannot meet all the insurance objectives, one should have a portfolio of policies covering all the needs.
To you, your car is almost another member of your family, and has the highest emotional value of all your investments. Any damage means both financial loss as well as loss of mobility.
The compulsory nature of the law protects you against third party liability as well.