Sharing doesn't imply e-mail. The user may choose to share the data to any available target. This could be email, a social network, a scrapbook app, etc.
The different data formats provided are supposed to be different views of the same data, not different data. How exactly a share target interprets the shared data is up to it, but typically they will use the most relevant format for the target.
See
Choosing data formats for sharing .
--Rob