I just wanted to echo the other users who have explained why this doesn't work for many workflows. As pasamio says, if I want individual files in a folder, there's already functionality for that purpose.
An optional setting to allow file previews inside a zip would be fine, but the whole point of a zip is to have a single, clearly marked file for download. Allowing users to dig around inside a zip is just confusing and defeats the purpose of providing users with a single file.