Yes, absolutely you need to carry automobile liability insurance in Massachusetts.
The minimum bodily injury policy requirement in Massachusetts is $20k/$40k. That means that if you cause an accident, and only one person is injured, that person can collect up to $20k in bodily injury payments from your auto insurance carrier. If you injure more than one person in the accident, than your auto insurance carrier is only required to pay a combined maximum of $40k in bodily injury payments to all people you injure in the accident.
It is always a wise idea to purchase as much liability as you can afford. You would be surprised how inexpensive it is to purchase additional liability protection.