If for no other reason, you need a will to name an executor (or executrix).
So, do you really need a will? Yes. Really.
A recent Forbes article titled "Do I Really Need a Will?" recommends that you should have a will to at least designate an executor or executrix to administer your estate. This individual will be responsible for taking care of your affairs after you pass away. Without a will, the probate court will appoint an administrator—this could end up being almost anyone. Anyone with a decent reason has the ability to petition the court to be appointed—like your cousin Reggie (who you last saw at your fourth birthday party) or your Uncle Ted (who is always dressed like it is 40 below, even in July).