"Do I Really Need A Will ?"
Yes. I have often told my clients that, for the money spent, a will is one of the best things you can do for yourself and your heirs. As I have stated elsewhere, without a doubt some of the biggest and unnecessary "messes" we have encountered over the years involve people who have passed away and not provided for their children or grandchildren through the use of a simple will.
We had a case years ago where one of the adult children was trying to by acreage in North Mississippi which belonged to his grandfather. After investigation we discovered that, along with 7 adult children still living, our client was having to deal with 15 grandchildren, all of whom were over the age of 21. As you would imagine, trying to get 22 people to understand what we were trying to do and reach a fair price, was impossible. (It only takes 1 to disagree.) As a result, our client had to purchase the property on the Courthouse steps for the value we had assigned to it in the first place. None of the other family members were present or interested in buying the property themselves. So, after a year and much expense, we cut 22 checks for different amounts to all the heirs, after first giving our client credit for all the money spent. All of the heirs happily picked up their checks.
A simple will executed by the grandparents would have solved the problem on the front end.
"What If Everything I Own Is Jointly Owned With My Spouse"
You still need at least a simple will. There may be assets out there that you thought were jointly owned but were not, or assets wherein one of you was the beneficiary instead of owning it jointly.