Today, many people manage their estate planning by titling their assets jointly so property will automatically pass to the survivor of the joint tenants without the necessity of probate. Or they may name a beneficiary to receive property directly upon death. Some place their assets in trust, also providing property will pass without the necessity for probate.
All these techniques work to avoid probate, so is a will really needed? The answer is Yes! Even if you believe all your property has been titled in a way that will avoid probate, you may have forgotten an asset. Or you may receive property by gift or in some other unexpected way (yes, you could win the lottery!) and not have time to title it the way you want.
A will does not eliminate the need for probate for assets held in your name alone, but it does ensure that your asset will pass according to your desires and not by way of intestate (dying without a will) succession. This is the scheme the state in which you reside has set up for you. It differs from state to state and may be quite different from your desires.
Consult an attorney to help you with your will. Kits and internet forms may not provide accurate information specific to the state in which you live.