Here is a good article from RocketLawyer on why you should have a Last Will and Testament.

5 Reasons You Should Create a Last Will

Although Wills and estate planning laws do vary state to state, one rule holds true: if you don’t have a Last Will and Testament, the Government makes one for you. That means your assets and estate are distributed according to the generic laws in your state. Generally, this means the government will split your belonging between your next of kin, spouse, and children. But who gets what? And who has to deal with actually distributing your assets? If you don’t make a Will during your life, the rules in your state make these decisions for you.

1- To appoint a guardian for your children

No one knows their children better than a parent and, if you pass away without a Last Will and Testament, the State will decide who should care for them. You can choose a guardian for your children in your Will and make sure they’re looked after by someone you love and trust.

2- To protect your business

Making a Last Will and Testament (and using Living Trusts) is a good way to pass your company to your heirs or the co-owners of your business. A full 70% of family owned businesses do not last past the first generation and the main reason for this is lack of estate planning.

3- To decide who receives your assets

Whether it’s a family heirloom, a classic Corvette, or your savings, you should decide who receives your belongings after you die, not generic state rules. These rules might not meet your wishes and never include provisions for those not related to you, like close friends or mentors. Make sure your loved ones get the assets you want them to receive.

4- To provide for a favorite charity

Wills don’t have to be just for friends, family, and loved ones. They can also be used for altruism. Including a charity in your Will is a great way to give back and make sure your assets are used for a good cause.

5- To make a difficult time less difficult

Losing someone is incredibly hard, and the last thing any of us want to do is spend those hard times haggling with lawyers and family members. Making a Will keeps your loved ones from having to deal with bureaucracy in a time of sadness.