What's new about this deal is that the ebook came first instead of being an afterthought. The book is short— about 30,000 words— and print nonfiction books are usually much longer. But in an ebook, length is less of an issue, and in addition, the format offered greater speed and less cost to the publisher, which translates to lower risk.
Gross' book, Dumb Money: How Our Greatest Financial Minds Bankrupted the Nation is still available on Kindle and Sony as well as being a trade paperback and an audiobook. Interestingly, there is another Kindle book from 2000 with a similar title: Dumb Money: Adventures of a Day Trader. The nine years between the books suggests maybe someone could have anticipated the current situation.