don't think oversaving is a big problem in American society today. I think that for most people, the bigger issue is spending too much and not saving enough. Also, taking on way too much debt in order to finance a luxurious lifestyle, usually at the expense of the future. Generally, most Americans already live with #1-#4 as prime guiding principles in their lifestyle and saving plans (not so sure about #5). People tend to live more for today, and not think so much about tomorrow.
One problem is that people are living longer and longer, but not saving as if they will live longer and longer. Many of us who are in our 40s and 50s today will live to be over 100. But most people's savings plans aren't designed around living to be over 100, because their parents or grandparents didn't live that long, and it was pretty rare until recently.
For the small percentage of true misers and oversavers out there, I agree that they should think about these principles and apply them in their lives. I definitely agree that the pendulum can swing too far in the other direction. But for the most part, it sounds like this book is trying to solve a problem that doesn't really exist, for most people.