Actually doing that from WOTC's end at this point is a bad idea. You have no way to reimburse people with a PDF copy or access code of their book because you cant confirm the sale of the book. Sure, you could send WOTC a picture of you holding a book, but there is no way to confirm whose book or even if the book has been bought and is not still in the game store or stolen. To try to o provide PDF/accesscodes from this point onward would require shrinkwrapped books with the code inside, removing perusal for future purchase consideration. Such a denial of perusal would have larger implications because many people are not impressed with some of the recent map illustrations in MAd MAge/Dungeon Heist and it has been stated even on these very forums that the maps were not what was expected by the majority(I like them). Plus as Pat and Vegemite has already covered, those books in Roll20 format come with additional usability beyond a textual book with pictures. the Monster Manual/Volos/Mordenkainens comes with tokens to move around. It is a great deal, like buying a $50ish hardcover book IRL and getting not only a single figure of each type listed but as many as you choose. You basically hit a gamestore jackpot on a real tabletop. Plus you have searchability function beyond flipping pages. Even the Players Handbook comes with figures for the PCs. WOTC's printing is basic in comparison. The Roll20 crew have put forth real effort so much that an access code would be tantamount to selling someone's else's token-making/web-hosting/search-function-programming/automatic-rolling/coding for free.
