I absolutely agree with the author. Cash flow projections are extremely important, but analyzing every possible detail of a business in a formal written plan seems a not so good use of time. One of the main keys to success in any business is flexibility. I've seen more than one example of slavishly following a business plan and turning off the creative juices that are such a large part of reason successful entrepreneurs are successful.
I've never had more than a spreadsheet for a "business plan". That doesn't mean that I didn't think through all of the important aspects of marketing, product, etc... To say that you should just donate the money to charity instead is flippant and not accurate as shown by the studies mentioned in the article.