Why Is The Attorney Saying My Dad Doesn't Need A Will In Iowa?

My dad's lives in Iowa, owns 83 acres of tillable farm land [in central Iowa], and has around $100k in cash in his bank account. He has stated several times that I am his only child and will inherit everything (this assumes medical expenses don't eat all of that up). I have asked him repeatedly to get a will but he keeps telling me that his lawyer says he does not need one. With a net worth around $1M (depending on land value) why would an attorney advise against getting a will?

I don't need the money. I just don't want for someone to come out of the woodworks claiming that the land is theirs or that they have a promise from him.