I must be missing something. Why would you ever want to do this?
* You can drag whatever you want in Finder & import into iPhoto
* iPhoto can import from the camera if you wish
* This method doesn't gain anything but seems to lose some image features

Why?

When your friend from university visits and she wants to share a single image with you she took on the way to your house, you can demonstrate to her your ability to take one image without having to import her entire camera full.

While there you have the opportunity to see what else she is interested in photographing thereby giving you ideas as to her intentions for you and perhaps ideas for Christmas gifts.

It's nice to have the option to download individual pictures, but up to now I've been using Image Capture for that. This iPhoto tip is just another way to do it.