This is a privacy concern. Whereas importing metadata is usually a good idea, exporting it should be a conscious action. A lot of private data can be leaked through metadata and many people don't realize it (which also usually means they don't need it). On the other hand, the people who realize it are the ones who would explicitly edit the metadata and check what they want to be exported or not.
This is only a first step. Some people may want to always export the metadata and for these people, there should be abilities to change the default.
096debb0fd Bug 790552 - do not save metadata by default.
plug-ins/common/file-png.c | 6 +++---
plug-ins/file-jpeg/jpeg-save.c | 6 +++---
plug-ins/file-tiff/file-tiff.c | 11 +++--------
plug-ins/file-webp/file-webp.c | 6 +++---
4 files changed, 12 insertions(+), 17 deletions(-)