I can not believe there was no export capability to produce an Epub2 file, let alone an eub3 file that meets the Daisy Consortium standards.
Yes, we'll add more export formats in future to support e-publications. (I'm not going to commit to exactly which ones.) For this initial 1.7 release we chose to coast with our existing PDF because we had so much else to do. We have left a lot of work to do over the coming years.