http://www.interference.com/stories/id179226.html
That is why U2 albums are not appended in expanded “legacy,” “anniversary,” or “special” editions. The music contained within them, and every nuance thereof, is enough to create a lasting and important statement, to achieve the desired communication of great artists. To show the artist’s sketchbook and reveal all the extraneous material destroys the integral and vital mystery of the work in creating a complete and satisfactory artistic work. The record is a statement, and revealing the inner working of how it was created dilutes the vision. Leave the albums alone, they don’t need expanding. They’re more than good enough as they are.