While last words of famous people are not important to memorize as a rule, they can be important to know in terms of literary analysis, especially when the person in question is famous for being a writer, diplomat or world leader. They can also be useful nuggets of information to hold onto for trivia contests.
There's no indication that anyone has ever had any special revelations while they lay dying. There have been some phrases uttered that were given meaning by the folks who heard them, or were remembered as being meaningful. It didn't make them particularly profound. Any number of geniuses and great thinkers through history died without uttering anything, let alone anything important.
The last words of famous people are not important for the public to know. It is private, and a family member may not wish to let the public know. In the end, it is more important to know how the person lived his or her life than any last words.
No, the last words of a famous person is not important because this person should be remembered and recognized for his or her words and actions while active in the community or society. The last words of a person are often skewed based on medications they are taking for pain or illnesses. In addition, the last words of a dying individual are often private and should remain within the family.