No Offline Access?

Our Open Bookshelf books aren't available in pdf or any e-book format for the following reasons:

• Toolchain. Producing readable and well-formatted books on all the various formats would require that we use a more sophisticated toolchain, along the lines that book publishers use. This adds more complexity to our process, which impedes publishing velocity.
• Frequent updates. We're constantly updating them with small fixes and tweaks. If we re-generate e-book versions after every fix, that means readers could be reading many different versions at any point in time. We want to avoid this problem and just have one master copy that's online.
• Media and links. We consider these natively online books and want to use the full features of webpages in them, including videos and links to other resources. This isn't possible for offline media.