If my players didn't have to buy all the books as individuals as well as my own copies, I'd love that. At the worst-case scenario, we all chip in a few dollars each for a new book and voila!, there it is on roll20. I love Drivethru RPG and I love roll20. I wasn't bothered by any implementation as long as they are accessible in-game: compendium or otherwise. Having that at our fingertips for complex games or specific situations would be great. Not all my players have multi-monitor set-ups, and have difficulty swapping between so many different pages while in the midst of a battle: roll20, pdfs, discord / skype / other, online SRDs, etc. The availability and sharing aspect is also what I love: tabletop shouldn't be about everyone having 10 copies of books each, it should be more about sitting down and playing. If my players want new books, I could just search and share. TL;DR: I love this idea!