There are, however, disadvantages.
There is still something of a format war going on. Publishers must support at least three formats and possibly four or five in order to ensure the best possible distribution.
In tandem with the format war there is a distribution channel war. Amazon wants you to buy through the Kindle store, Apple wants you to buy through the iBooks store, B&N wants you to buy from the Nook store. Authors want you to buy direct from their websites so they can get higher margins.
All of this creates a huge amount of unnecessary work for the author/publisher.