The Tags you can add to Images are stored in the Imagefiles itself. Actually, that causes, every changes on the Tagcloud the timestamp of the file is updated on the filesystem.
So when you copy Pictures from last christmas on your device and the Date and Time of the File are important for you avoid adding tags to it. (At example to know when you have modify the Image the last time)
Many Tag Editors for mp3 Files had this problem also in the past. Currently the most of this tag Editors are keeping file Date and Time when only the Tags in the Files are modified and not the content (the mp3 song) itself.
Edit the Image and store (and compress it again) is a other case. Then you have modify the image and the Time and Date on the File system should be updated. Sometimes you want to know when you have modified the picture the last time. Not when you have added the Tags to it.
Same Issue when you only rotate a image with the loseless process.
Here you can Find the Discussion on talk.maemo.org: LINK
